diff --git a/src/battle.c b/src/battle.c
index 23c219109..9864adc41 100644
--- a/src/battle.c
+++ b/src/battle.c
@@ -1059,7 +1059,7 @@ static int rc_specialdamage(const unit *au, const unit *du, const struct weapon_
     return modifier;
 }
 
-int calculate_armor(troop dt, const weapon_type *dwtype, const weapon_type *awtype, double *magres) {
+int calculate_armor(troop dt, const weapon_type *dwtype, const weapon_type *awtype, variant *magres) {
     fighter *df = dt.fighter;
     unit *du = df->unit;
     int ar = 0, an, am;
@@ -1110,21 +1110,31 @@ int calculate_armor(troop dt, const weapon_type *dwtype, const weapon_type *awty
 
     if (magres) {
         /* calculate damage multiplier for magical damage */
-        double res = 1.0 - magic_resistance(du);
+        variant res;
+        
+        res = frac_sub(frac_one, magic_resistance(du));
 
         if (u_race(du)->battle_flags & BF_EQUIPMENT) {
             /* der Effekt von Laen steigt nicht linear */
-            if (armor && fval(armor, ATF_LAEN))
-                res *= (1 - armor->magres);
-            if (shield && fval(shield, ATF_LAEN))
-                res *= (1 - shield->magres);
-            if (dwtype)
-                res *= (1 - dwtype->magres);
+            if (armor && fval(armor, ATF_LAEN)) {
+                res = frac_mul(res, frac_sub(frac_one, armor->magres));
+            }
+            if (shield && fval(shield, ATF_LAEN)) {
+                res = frac_mul(res, frac_sub(frac_one, shield->magres));
+            }
+            if (dwtype) {
+                res = frac_mul(res, frac_sub(frac_one, dwtype->magres));
+            }
         }
 
-        /* gegen Magie wirkt nur nat�rliche und magische R�stung */
+        /* gegen Magie wirkt nur natuerliche und magische Ruestung */
         ar = an + am;
-        *magres = res > 0 ? res : 0;
+        if (res.sa[0] >= 0) {
+            *magres = res;
+        }
+        else {
+            *magres = frac_make(0, 1);
+        }
     }
 
     return ar;
@@ -1147,7 +1157,7 @@ terminate(troop dt, troop at, int type, const char *damage, bool missile)
     const weapon_type *dwtype = NULL;
     const weapon_type *awtype = NULL;
     const weapon *weapon;
-    double res = 1.0;
+    variant res = frac_make(1, 1);
 
     int rda, sk = 0, sd;
     bool magic = false;
@@ -1190,9 +1200,9 @@ terminate(troop dt, troop at, int type, const char *damage, bool missile)
         return false;
     }
 
-    /* TODO not sure if res could be > 1 here */
     if (magic) {
-        da = (int)(MAX(da * res, 0));
+        res = frac_mul(frac_make(da, 1), res);
+        da = res.sa[0] / res.sa[1];
     }
 
     if (type != AT_COMBATSPELL && type != AT_SPELL) {
diff --git a/src/battle.h b/src/battle.h
index 1b4cf2588..85e65cf66 100644
--- a/src/battle.h
+++ b/src/battle.h
@@ -248,7 +248,7 @@ extern "C" {
     int count_enemies(struct battle *b, const struct fighter *af,
         int minrow, int maxrow, int select);
     int natural_armor(struct unit * u);
-    int calculate_armor(troop dt, const struct weapon_type *dwtype, const struct weapon_type *awtype, double *magres);
+    int calculate_armor(troop dt, const struct weapon_type *dwtype, const struct weapon_type *awtype, union variant *magres);
     bool terminate(troop dt, troop at, int type, const char *damage,
         bool missile);
     extern void message_all(battle * b, struct message *m);
diff --git a/src/battle.test.c b/src/battle.test.c
index d15c335a9..b00d06a98 100644
--- a/src/battle.test.c
+++ b/src/battle.test.c
@@ -250,23 +250,24 @@ static void test_calculate_armor(CuTest * tc)
     armor_type *ashield, *achain;
     item_type *ibelt, *ishield, *ichain;
     race *rc;
-    double magres = 0.0;
+    variant magres = frac_zero;
+    variant v50p = frac_make(1, 2);
 
     test_setup();
     r = test_create_region(0, 0, 0);
     ibelt = it_get_or_create(rt_get_or_create("trollbelt"));
     ishield = it_get_or_create(rt_get_or_create("shield"));
-    ashield = new_armortype(ishield, 0.0, 0.5, 1, ATF_SHIELD);
+    ashield = new_armortype(ishield, 0.0, v50p, 1, ATF_SHIELD);
     ichain = it_get_or_create(rt_get_or_create("chainmail"));
-    achain = new_armortype(ichain, 0.0, 0.5, 3, ATF_NONE);
-    wtype = new_weapontype(it_get_or_create(rt_get_or_create("sword")), 0, 0.5, 0, 0, 0, 0, SK_MELEE, 1);
+    achain = new_armortype(ichain, 0.0, v50p, 3, ATF_NONE);
+    wtype = new_weapontype(it_get_or_create(rt_get_or_create("sword")), 0, v50p, 0, 0, 0, 0, SK_MELEE, 1);
     rc = test_create_race("human");
     du = test_create_unit(test_create_faction(rc), r);
     dt.index = 0;
 
     dt.fighter = setup_fighter(&b, du);
     CuAssertIntEquals_Msg(tc, "default ac", 0, calculate_armor(dt, 0, 0, &magres));
-    CuAssertDblEquals_Msg(tc, "magres unmodified", 1.0, magres, 0.01);
+    CuAssertIntEquals_Msg(tc, "magres unmodified", magres.sa[0], magres.sa[1]);
     free_battle(b);
 
     b = NULL;
@@ -299,13 +300,13 @@ static void test_calculate_armor(CuTest * tc)
     wtype->flags = WTF_NONE;
 
     CuAssertIntEquals_Msg(tc, "magical attack", 3, calculate_armor(dt, 0, 0, &magres));
-    CuAssertDblEquals_Msg(tc, "magres unmodified", 1.0, magres, 0.01);
+    CuAssertIntEquals_Msg(tc, "magres unmodified", magres.sa[1], magres.sa[0]);
 
     ashield->flags |= ATF_LAEN;
     achain->flags |= ATF_LAEN;
-    magres = 1.0;
+    magres = frac_one;
     CuAssertIntEquals_Msg(tc, "laen armor", 3, calculate_armor(dt, 0, 0, &magres));
-    CuAssertDblEquals_Msg(tc, "laen magres bonus", 0.25, magres, 0.01);
+    CuAssertIntEquals_Msg(tc, "laen magres bonus", 4, magres.sa[1]);
     free_battle(b);
     test_cleanup();
 }
@@ -319,38 +320,42 @@ static void test_magic_resistance(CuTest *tc)
     armor_type *ashield, *achain;
     item_type *ishield, *ichain;
     race *rc;
-    double magres;
+    variant magres;
+    variant v50p = frac_make(1, 2);
+    variant v10p = frac_make(1, 10);
 
     test_setup();
     r = test_create_region(0, 0, 0);
     ishield = it_get_or_create(rt_get_or_create("shield"));
-    ashield = new_armortype(ishield, 0.0, 0.5, 1, ATF_SHIELD);
+    ashield = new_armortype(ishield, 0.0, v50p, 1, ATF_SHIELD);
     ichain = it_get_or_create(rt_get_or_create("chainmail"));
-    achain = new_armortype(ichain, 0.0, 0.5, 3, ATF_NONE);
+    achain = new_armortype(ichain, 0.0, v50p, 3, ATF_NONE);
     rc = test_create_race("human");
     du = test_create_unit(test_create_faction(rc), r);
     dt.index = 0;
 
+    i_change(&du->items, ishield, 1);
     dt.fighter = setup_fighter(&b, du);
     calculate_armor(dt, 0, 0, &magres);
-    CuAssertDblEquals_Msg(tc, "no magres bonus", 0.0, magic_resistance(du), 0.01);
-    CuAssertDblEquals_Msg(tc, "no magres reduction", 1.0, magres, 0.01);
+    CuAssertIntEquals_Msg(tc, "no magres reduction", magres.sa[1], magres.sa[0]);
+    magres = magic_resistance(du);
+    CuAssertIntEquals_Msg(tc, "no magres reduction", 0, magres.sa[0]);
 
     ashield->flags |= ATF_LAEN;
-    ashield->magres = 0.1;
+    ashield->magres = v10p;
     calculate_armor(dt, 0, 0, &magres);
+    CuAssert(tc, "laen reduction => 10%%", frac_equal(frac_make(9, 10), magres));
     free_battle(b);
 
     b = NULL;
-    i_change(&du->items, ishield, 1);
     i_change(&du->items, ichain, 1);
     achain->flags |= ATF_LAEN;
-    achain->magres = 0.1;
+    achain->magres = v10p;
     ashield->flags |= ATF_LAEN;
-    ashield->magres = 0.1;
+    ashield->magres = v10p;
     dt.fighter = setup_fighter(&b, du);
     calculate_armor(dt, 0, 0, &magres);
-    CuAssertDblEquals_Msg(tc, "laen reduction", 0.81, magres, 0.01);
+    CuAssert(tc, "2x laen reduction => 81%%", frac_equal(frac_make(81, 100), magres));
     free_battle(b);
 
     b = NULL;
@@ -359,17 +364,20 @@ static void test_magic_resistance(CuTest *tc)
     set_level(du, SK_MAGIC, 2);
     dt.fighter = setup_fighter(&b, du);
     calculate_armor(dt, 0, 0, &magres);
-    CuAssertDblEquals_Msg(tc, "skill bonus", 0.1, magic_resistance(du), 0.01);
-    CuAssertDblEquals_Msg(tc, "skill reduction", 0.9, magres, 0.01);
-    rc->magres = 50; /* percentage, gets added to skill bonus */
+    CuAssert(tc, "skill reduction => 90%%", frac_equal(magres, frac_make(9, 10)));
+    magres = magic_resistance(du);
+    CuAssert(tc, "skill reduction", frac_equal(magres, v10p));
+    rc->magres = v50p; /* percentage, gets added to skill bonus */
     calculate_armor(dt, 0, 0, &magres);
-    CuAssertDblEquals_Msg(tc, "race bonus", 0.6, magic_resistance(du), 0.01);
-    CuAssertDblEquals_Msg(tc, "race reduction", 0.4, magres, 0.01);
+    CuAssert(tc, "race reduction => 40%%", frac_equal(magres, frac_make(4, 10)));
+    magres = magic_resistance(du);
+    CuAssert(tc, "race bonus => 60%%", frac_equal(magres, frac_make(60, 100)));
 
-    rc->magres = 150; /* should not cause negative damage multiplier */
-    CuAssertDblEquals_Msg(tc, "magic resistance is never > 0.9", 0.9, magic_resistance(du), 0.01);
+    rc->magres = frac_make(15, 10); /* 150% resistance should not cause negative damage multiplier */
+    magres = magic_resistance(du);
+    CuAssert(tc, "magic resistance is never > 0.9", frac_equal(magres, frac_make(9, 10)));
     calculate_armor(dt, 0, 0, &magres);
-    CuAssertDblEquals_Msg(tc, "damage reduction is never < 0.1", 0.1, magres, 0.01);
+    CuAssert(tc, "damage reduction is never < 0.1", frac_equal(magres, frac_make(1, 10)));
 
     free_battle(b);
     test_cleanup();
@@ -385,14 +393,15 @@ static void test_projectile_armor(CuTest * tc)
     armor_type *ashield, *achain;
     item_type *ishield, *ichain;
     race *rc;
+    variant v50p = frac_make(1, 2);
 
     test_setup();
     r = test_create_region(0, 0, 0);
     ishield = it_get_or_create(rt_get_or_create("shield"));
-    ashield = new_armortype(ishield, 0.0, 0.5, 1, ATF_SHIELD);
+    ashield = new_armortype(ishield, 0.0, v50p, 1, ATF_SHIELD);
     ichain = it_get_or_create(rt_get_or_create("chainmail"));
-    achain = new_armortype(ichain, 0.0, 0.5, 3, ATF_NONE);
-    wtype = new_weapontype(it_get_or_create(rt_get_or_create("sword")), 0, 0.5, 0, 0, 0, 0, SK_MELEE, 1);
+    achain = new_armortype(ichain, 0.0, v50p, 3, ATF_NONE);
+    wtype = new_weapontype(it_get_or_create(rt_get_or_create("sword")), 0, v50p, 0, 0, 0, 0, SK_MELEE, 1);
     rc = test_create_race("human");
     rc->battle_flags |= BF_EQUIPMENT;
     du = test_create_unit(test_create_faction(rc), r);
diff --git a/src/economy.test.c b/src/economy.test.c
index 2de6265f0..4ddd20105 100644
--- a/src/economy.test.c
+++ b/src/economy.test.c
@@ -211,7 +211,7 @@ static void test_tax_cmd(CuTest *tc) {
     silver = get_resourcetype(R_SILVER)->itype;
 
     sword = it_get_or_create(rt_get_or_create("sword"));
-    new_weapontype(sword, 0, 0.0, NULL, 0, 0, 0, SK_MELEE, 1);
+    new_weapontype(sword, 0, frac_zero, NULL, 0, 0, 0, SK_MELEE, 1);
     i_change(&u->items, sword, 1);
     set_level(u, SK_MELEE, 1);
 
diff --git a/src/guard.test.c b/src/guard.test.c
index fb55129ee..17aa2891c 100644
--- a/src/guard.test.c
+++ b/src/guard.test.c
@@ -42,7 +42,7 @@ static void test_guard_unskilled(CuTest * tc)
 
     test_setup();
     itype = it_get_or_create(rt_get_or_create("sword"));
-    new_weapontype(itype, 0, 0.0, NULL, 0, 0, 0, SK_MELEE, 2);
+    new_weapontype(itype, 0, frac_zero, NULL, 0, 0, 0, SK_MELEE, 2);
     r = test_create_region(0, 0, 0);
     u = test_create_unit(test_create_faction(0), r);
     ug = test_create_unit(test_create_faction(0), r);
@@ -61,7 +61,7 @@ static void test_guard_armed(CuTest * tc)
 
     test_setup();
     itype = it_get_or_create(rt_get_or_create("sword"));
-    new_weapontype(itype, 0, 0.0, NULL, 0, 0, 0, SK_MELEE, 2);
+    new_weapontype(itype, 0, frac_zero, NULL, 0, 0, 0, SK_MELEE, 2);
     r = test_create_region(0, 0, 0);
     u = test_create_unit(test_create_faction(0), r);
     ug = test_create_unit(test_create_faction(0), r);
@@ -80,7 +80,7 @@ static void test_is_guard(CuTest * tc)
 
     test_setup();
     itype = it_get_or_create(rt_get_or_create("sword"));
-    new_weapontype(itype, 0, 0.0, NULL, 0, 0, 0, SK_MELEE, 2);
+    new_weapontype(itype, 0, frac_zero, NULL, 0, 0, 0, SK_MELEE, 2);
     r = test_create_region(0, 0, 0);
     ug = test_create_unit(test_create_faction(0), r);
     i_change(&ug->items, itype, 1);
diff --git a/src/kernel/building.h b/src/kernel/building.h
index 8c23fdb7c..6d66aa9ab 100644
--- a/src/kernel/building.h
+++ b/src/kernel/building.h
@@ -60,7 +60,7 @@ extern "C" {
         int capacity;               /* Kapazit�t pro Gr��enpunkt */
         int maxcapacity;            /* Max. Kapazit�t */
         int maxsize;                /* how big can it get, with all the extensions? */
-        int magres;                 /* how well it resists against spells */
+        variant magres;                 /* how well it resists against spells */
         int magresbonus;            /* bonus it gives the target against spells */
         int fumblebonus;            /* bonus that reduces fumbling */
         double auraregen;           /* modifier for aura regeneration inside building */
diff --git a/src/kernel/building.test.c b/src/kernel/building.test.c
index 1286fd6b4..2819d4a16 100644
--- a/src/kernel/building.test.c
+++ b/src/kernel/building.test.c
@@ -381,7 +381,7 @@ static void test_btype_defaults(CuTest *tc) {
     CuAssertIntEquals(tc, -1, btype->maxsize);
     CuAssertIntEquals(tc, 1, btype->capacity);
     CuAssertIntEquals(tc, -1, btype->maxcapacity);
-    CuAssertIntEquals(tc, 0, btype->magres);
+    CuAssertIntEquals(tc, 0, btype->magres.sa[0]);
     CuAssertIntEquals(tc, 0, btype->magresbonus);
     CuAssertIntEquals(tc, 0, btype->fumblebonus);
     CuAssertIntEquals(tc, 0, btype->flags);
diff --git a/src/kernel/item.c b/src/kernel/item.c
index 9bc321fdb..6e64c147f 100644
--- a/src/kernel/item.c
+++ b/src/kernel/item.c
@@ -275,7 +275,7 @@ luxury_type *new_luxurytype(item_type * itype, int price)
 }
 
 weapon_type *new_weapontype(item_type * itype,
-    int wflags, double magres, const char *damage[], int offmod, int defmod,
+    int wflags, variant magres, const char *damage[], int offmod, int defmod,
     int reload, skill_t sk, int minskill)
 {
     weapon_type *wtype;
@@ -301,7 +301,7 @@ weapon_type *new_weapontype(item_type * itype,
     return wtype;
 }
 
-armor_type *new_armortype(item_type * itype, double penalty, double magres,
+armor_type *new_armortype(item_type * itype, double penalty, variant magres,
     int prot, unsigned int flags)
 {
     armor_type *atype;
diff --git a/src/kernel/item.h b/src/kernel/item.h
index 1d3e5ff29..c1ac38517 100644
--- a/src/kernel/item.h
+++ b/src/kernel/item.h
@@ -181,7 +181,7 @@ extern "C" {
         const item_type *itype;
         unsigned int flags;
         double penalty;
-        double magres;
+        variant magres;
         int prot;
         float projectile;           /* chance, dass ein projektil abprallt */
     } armor_type;
@@ -205,7 +205,7 @@ extern "C" {
         int minskill;
         int offmod;
         int defmod;
-        double magres;
+        variant magres;
         int reload;                 /* time to reload this weapon */
         weapon_mod *modifiers;
         /* --- functions --- */
@@ -244,14 +244,12 @@ extern "C" {
     /* creation */
     resource_type *rt_get_or_create(const char *name);
     item_type *it_get_or_create(resource_type *rtype);
-    item_type *new_itemtype(resource_type * rtype, int iflags, int weight,
-        int capacity);
     luxury_type *new_luxurytype(item_type * itype, int price);
     weapon_type *new_weapontype(item_type * itype, int wflags,
-        double magres, const char *damage[], int offmod, int defmod, int reload,
+        variant magres, const char *damage[], int offmod, int defmod, int reload,
         skill_t sk, int minskill);
     armor_type *new_armortype(item_type * itype, double penalty,
-        double magres, int prot, unsigned int flags);
+        variant magres, int prot, unsigned int flags);
     potion_type *new_potiontype(item_type * itype, int level);
 
     typedef enum {
diff --git a/src/kernel/jsonconf.c b/src/kernel/jsonconf.c
index 2478c838f..287aa61db 100644
--- a/src/kernel/jsonconf.c
+++ b/src/kernel/jsonconf.c
@@ -460,7 +460,7 @@ static void json_race(cJSON *json, race *rc) {
             break;
         case cJSON_Number:
             if (strcmp(child->string, "magres") == 0) {
-                rc->magres = child->valueint;
+                rc->magres = frac_make(child->valueint, 100);
             }
             else if (strcmp(child->string, "maxaura") == 0) {
                 rc->maxaura = child->valueint;
diff --git a/src/kernel/jsonconf.test.c b/src/kernel/jsonconf.test.c
index dcf748d00..8b8ac8c14 100644
--- a/src/kernel/jsonconf.test.c
+++ b/src/kernel/jsonconf.test.c
@@ -163,8 +163,7 @@ static void test_races(CuTest * tc)
     CuAssertPtrNotNull(tc, rc);
     CuAssertIntEquals(tc, RCF_NPC | RCF_WALK | RCF_UNDEAD, rc->flags);
     CuAssertStrEquals(tc, "1d4", rc->def_damage);
-    CuAssertIntEquals(tc, 100, rc->magres);
-    CuAssertDblEquals(tc, 1.0, rc_magres(rc), 0.0);
+    CuAssertTrue(tc, frac_equal(frac_one, rc->magres));
     CuAssertIntEquals(tc, 200, rc->maxaura);
     CuAssertDblEquals(tc, 2.0, rc_maxaura(rc), 0.0);
     CuAssertDblEquals(tc, 3.0, rc->regaura, 0.0);
diff --git a/src/kernel/race.c b/src/kernel/race.c
index 4a3a04916..d159fd6d8 100644
--- a/src/kernel/race.c
+++ b/src/kernel/race.c
@@ -331,6 +331,7 @@ race *rc_create(const char *zName)
 
     assert(zName);
     rc = (race *)calloc(sizeof(race), 1);
+    rc->magres.sa[1] = 1;
     rc->hitpoints = 1;
     rc->weight = PERSON_WEIGHT;
     rc->capacity = 540;
@@ -383,8 +384,8 @@ bool r_insectstalled(const region * r)
     return fval(r->terrain, ARCTIC_REGION);
 }
 
-double rc_magres(const race *rc) {
-    return rc->magres / 100.0;
+variant rc_magres(const race *rc) {
+    return rc->magres;
 }
 
 double rc_maxaura(const race *rc) {
diff --git a/src/kernel/race.h b/src/kernel/race.h
index e464c9447..f14b8e54f 100644
--- a/src/kernel/race.h
+++ b/src/kernel/race.h
@@ -116,7 +116,7 @@ extern "C" {
 
     typedef struct race {
         char *_name;
-        int magres;
+        variant magres;
         int healing;
         int maxaura;            /* Faktor auf Maximale Aura */
         double regaura;            /* Faktor auf Regeneration */
@@ -182,7 +182,7 @@ extern "C" {
 
     int rc_luxury_trade(const struct race *rc);
     int rc_herb_trade(const struct race *rc);
-    double rc_magres(const struct race *rc);
+    variant rc_magres(const struct race *rc);
     double rc_maxaura(const struct race *rc);
     int rc_armor_bonus(const struct race *rc);
     int rc_scare(const struct race *rc);
diff --git a/src/kernel/race.test.c b/src/kernel/race.test.c
index 8363d8b72..07ecbdd45 100644
--- a/src/kernel/race.test.c
+++ b/src/kernel/race.test.c
@@ -24,8 +24,7 @@ static void test_rc_defaults(CuTest *tc) {
     rc = rc_get_or_create("human");
     CuAssertStrEquals(tc, "human", rc->_name);
     CuAssertIntEquals(tc, 0, rc_armor_bonus(rc));
-    CuAssertIntEquals(tc, 0, rc->magres);
-    CuAssertDblEquals(tc, 0.0, rc_magres(rc), 0.0);
+    CuAssertIntEquals(tc, 0, rc->magres.sa[0]);
     CuAssertIntEquals(tc, 0, rc->healing);
     CuAssertDblEquals(tc, 0.0, rc_maxaura(rc), 0.0);
     CuAssertDblEquals(tc, 1.0, rc->recruit_multi, 0.0);
diff --git a/src/kernel/xmlreader.c b/src/kernel/xmlreader.c
index 27adba598..74459270c 100644
--- a/src/kernel/xmlreader.c
+++ b/src/kernel/xmlreader.c
@@ -61,6 +61,19 @@ without prior permission by the authors of Eressea.
 #include <string.h>
 
 #ifdef USE_LIBXML2
+
+static variant xml_fraction(xmlNodePtr node, const char *name) {
+    xmlChar *propValue = xmlGetProp(node, BAD_CAST name);
+    if (propValue != NULL) {
+        int num, den = 100;
+        double fval = atof((const char *)propValue);
+        num = (int)(fval * den + 0.5);
+        xmlFree(propValue);
+        return frac_make(num, den);
+    }
+    return frac_make(0, 1);
+}
+
 static void xml_readtext(xmlNodePtr node, struct locale **lang, xmlChar ** text)
 {
     xmlChar *propValue = xmlGetProp(node, BAD_CAST "locale");
@@ -245,7 +258,7 @@ static int parse_buildings(xmlDocPtr doc)
             btype->maxcapacity = xml_ivalue(node, "maxcapacity", btype->maxcapacity);
             btype->maxsize = xml_ivalue(node, "maxsize", btype->maxsize);
 
-            btype->magres = xml_ivalue(node, "magres", btype->magres);
+            btype->magres = frac_make(xml_ivalue(node, "magres", 0), 100);
             btype->magresbonus = xml_ivalue(node, "magresbonus", btype->magresbonus);
             btype->fumblebonus = xml_ivalue(node, "fumblebonus", btype->fumblebonus);
             btype->auraregen = xml_fvalue(node, "auraregen", btype->auraregen);
@@ -582,7 +595,7 @@ static armor_type *xml_readarmor(xmlXPathContextPtr xpath, item_type * itype)
     unsigned int flags = ATF_NONE;
     int ac = xml_ivalue(node, "ac", 0);
     double penalty = xml_fvalue(node, "penalty", 0.0);
-    double magres = xml_fvalue(node, "magres", 0.0);
+    variant magres = xml_fraction(node, "magres");
 
     if (xml_bvalue(node, "laen", false))
         flags |= ATF_LAEN;
@@ -607,7 +620,7 @@ static weapon_type *xml_readweapon(xmlXPathContextPtr xpath, item_type * itype)
     int offmod = xml_ivalue(node, "offmod", 0);
     int defmod = xml_ivalue(node, "defmod", 0);
     int reload = xml_ivalue(node, "reload", 0);
-    double magres = xml_fvalue(node, "magres", 0.0);
+    variant magres = xml_fraction(node, "magres");
 
     if (xml_bvalue(node, "armorpiercing", false))
         flags |= WTF_ARMORPIERCING;
@@ -899,22 +912,6 @@ static int parse_rules(xmlDocPtr doc)
     return 0;
 }
 
-static int gcd(int num, int den) {
-    const int primes[] = { 3, 5, 7, 11, 0 };
-    int i=0, g = 1, p = 2;
-    while (p && p<=den && p<=num) {
-        if (num % p == 0 && den % p == 0) {
-            num /= p;
-            den /= p;
-            g *= p;
-        }
-        else {
-            p = primes[i++];
-        }
-    }
-    return g;
-}
-
 static int parse_resources(xmlDocPtr doc)
 {
     xmlXPathContextPtr xpath = xmlXPathNewContext(doc);
@@ -1031,15 +1028,7 @@ static int parse_resources(xmlDocPtr doc)
                         rdata->modifiers[k].flags = RMF_SKILL;
                     }
                     else if (strcmp((const char *)propValue, "material") == 0) {
-                        int g, num, den = 100;
-                        double fval = xml_fvalue(node, "value", 0);
-                        /* TODO: extract into a function for reading fractions? */
-                        num = (int)(fval * den + 0.5);
-                        g = gcd(num, den);
-                        num /= g;
-                        den /= g;
-                        rdata->modifiers[k].value.sa[0] = (short)num;
-                        rdata->modifiers[k].value.sa[1] = (short)den;
+                        rdata->modifiers[k].value = xml_fraction(node, "value");
                         rdata->modifiers[k].flags = RMF_SAVEMATERIAL;
                     }
                     else if (strcmp((const char *)propValue, "require") == 0) {
@@ -1623,7 +1612,7 @@ static int parse_races(xmlDocPtr doc)
         rc->def_damage = strdup((const char *)propValue);
         xmlFree(propValue);
 
-        rc->magres = xml_ivalue(node, "magres", rc->magres);
+        rc->magres = frac_make(xml_ivalue(node, "magres", 100), 100);
         rc->healing = (int)(xml_fvalue(node, "healing", rc->healing) * 100); /* TODO: store as int in XML */
         rc->maxaura = (int)(xml_fvalue(node, "maxaura", rc->maxaura) * 100); /* TODO: store as int in XML */
         rc->regaura = (float)xml_fvalue(node, "regaura", rc->regaura);
diff --git a/src/laws.test.c b/src/laws.test.c
index cca55beb1..c27651d83 100644
--- a/src/laws.test.c
+++ b/src/laws.test.c
@@ -611,7 +611,7 @@ void setup_guard(guard_fixture *fix, bool armed) {
     if (armed) {
         item_type *itype;
         itype = it_get_or_create(rt_get_or_create("sword"));
-        new_weapontype(itype, 0, 0.0, NULL, 0, 0, 0, SK_MELEE, 2);
+        new_weapontype(itype, 0, frac_zero, NULL, 0, 0, 0, SK_MELEE, 2);
         i_change(&u->items, itype, 1);
         set_level(u, SK_MELEE, 2);
     }
@@ -1481,7 +1481,7 @@ static void test_armedmen(CuTest *tc) {
     test_setup();
     u = test_create_unit(test_create_faction(0), test_create_region(0, 0, 0));
     it_sword = test_create_itemtype("sword");
-    wtype = new_weapontype(it_sword, 0, 0.5, 0, 0, 0, 0, SK_MELEE, 1);
+    wtype = new_weapontype(it_sword, 0, frac_make(1, 2), 0, 0, 0, 0, SK_MELEE, 1);
     CuAssertIntEquals(tc, 0, armedmen(u, false));
     CuAssertIntEquals(tc, 0, armedmen(u, true));
     set_level(u, SK_MELEE, 1);
diff --git a/src/magic.c b/src/magic.c
index 65b454c04..de1336d66 100644
--- a/src/magic.c
+++ b/src/magic.c
@@ -1135,27 +1135,29 @@ static int farcasting(unit * magician, region * r)
 
 /* allgemeine Magieresistenz einer Einheit,
  * reduziert magischen Schaden */
-double magic_resistance(unit * target)
+variant magic_resistance(unit * target)
 {
     attrib *a;
     curse *c;
     const curse_type * ct_goodresist = 0, *ct_badresist = 0;
     const resource_type *rtype;
     const race *rc = u_race(target);
-    double probability = rc_magres(rc);
+    variant v, prob = rc_magres(rc);
     const plane *pl = rplane(target->region);
 
     if (rc == get_race(RC_HIRNTOETER) && !pl) {
-        probability /= 2;
+        prob.sa[1] *= 2;
     }
     assert(target->number > 0);
     /* Magier haben einen Resistenzbonus vom Magietalent * 5% */
-    probability += effskill(target, SK_MAGIC, 0) * 0.05;
+    prob = frac_add(prob, frac_make(effskill(target, SK_MAGIC, 0), 20));
 
     /* Auswirkungen von Zaubern auf der Einheit */
     c = get_curse(target->attribs, ct_find("magicresistance"));
     if (c) {
-        probability += 0.01 * curse_geteffect(c) * get_cursedmen(target, c);
+        /* TODO: legacy. magicresistance-effect is an integer-percentage stored in a double */
+        int effect = curse_geteffect_int(c) * get_cursedmen(target, c);
+        prob = frac_add(prob, frac_make(effect, 100));
     }
 
     /* Unicorn +10 */
@@ -1163,7 +1165,7 @@ double magic_resistance(unit * target)
     if (rtype) {
         int n = i_get(target->items, rtype->itype);
         if (n) {
-            probability += n * 0.1 / target->number;
+            prob = frac_add(prob, frac_make(n, target->number * 10));
         }
     }
 
@@ -1180,13 +1182,15 @@ double magic_resistance(unit * target)
         if (mage != NULL) {
             if (ct_goodresist && c->type == ct_goodresist) {
                 if (alliedunit(mage, target->faction, HELP_GUARD)) {
-                    probability += curse_geteffect(c) * 0.01;
+                    /* TODO: legacy. magicresistance-effect is an integer-percentage stored in a double */
+                    prob = frac_add(prob, frac_make(curse_geteffect_int(c), 100));
                     ct_goodresist = 0; /* only one effect per region */
                 }
             }
             else if (ct_badresist && c->type == ct_badresist) {
                 if (!alliedunit(mage, target->faction, HELP_GUARD)) {
-                    probability -= curse_geteffect(c) * 0.01;
+                    /* TODO: legacy. magicresistance-effect is an integer-percentage stored in a double */
+                    prob = frac_sub(prob, frac_make(curse_geteffect_int(c), 100));
                     ct_badresist = 0; /* only one effect per region */
                 }
             }
@@ -1202,11 +1206,18 @@ double magic_resistance(unit * target)
         const struct building_type *btype = building_is_active(b) ? b->type : NULL;
 
         /* gesegneter Steinkreis gibt 30% dazu */
-        if (btype)
-            probability += btype->magresbonus * 0.01;
+        if (btype) {
+            /* TODO: legacy. building-bonus is an integer-percentage */
+            prob = frac_add(prob, frac_make(btype->magresbonus, 100));
+        }
     }
 
-    return (probability<0.9) ? probability : 0.9;
+    /* resistance must never be more than 90% */
+    v = frac_make(9, 10);
+    if (frac_sign(frac_sub(prob, v)) > 0) { /* prob < 90% */
+        return v; /* at most 90% */
+    }
+    return prob;
 }
 
 /* ------------------------------------------------------------- */
@@ -1223,12 +1234,12 @@ double magic_resistance(unit * target)
 bool
 target_resists_magic(unit * magician, void *obj, int objtyp, int t_bonus)
 {
-    double probability = 0.0;
+    variant v02p, v98p, prob = frac_make(t_bonus, 100);
+    attrib *a = NULL;
 
-    if (magician == NULL)
-        return true;
-    if (obj == NULL)
+    if (magician == NULL || obj == NULL) {
         return true;
+    }
 
     switch (objtyp) {
     case TYP_UNIT:
@@ -1248,43 +1259,56 @@ target_resists_magic(unit * magician, void *obj, int objtyp, int t_bonus)
                 pa = sk;
         }
 
-        /* Contest */
-        probability = 0.05 * (10 + pa - at);
-
-        probability += magic_resistance((unit *)obj);
+        /* Contest, probability = 0.05 * (10 + pa - at); */
+        prob = frac_add(prob, frac_make(10 + pa - at, 20));
+        prob = frac_add(prob, magic_resistance((unit *)obj));
         break;
     }
 
     case TYP_REGION:
-        /* Bonus durch Zauber */
+        /* Bonus durch Zauber
         probability +=
-            0.01 * get_curseeffect(((region *)obj)->attribs, C_RESIST_MAGIC, 0);
+            0.01 * get_curseeffect(((region *)obj)->attribs, C_RESIST_MAGIC, 0); */
+        a = ((region *)obj)->attribs;
         break;
 
     case TYP_BUILDING:
-        /* Bonus durch Zauber */
+        /* Bonus durch Zauber
         probability +=
-            0.01 * get_curseeffect(((building *)obj)->attribs, C_RESIST_MAGIC, 0);
-
-        /* Bonus durch Typ */
-        probability += 0.01 * ((building *)obj)->type->magres;
-
+            0.01 * get_curseeffect(((building *)obj)->attribs, C_RESIST_MAGIC, 0); */
+        a = ((building *)obj)->attribs;
+        /* Bonus durch Typ
+        probability += 0.01 * ((building *)obj)->type->magres; */
+        prob = frac_add(prob, ((building *)obj)->type->magres);
         break;
 
     case TYP_SHIP:
         /* Bonus durch Zauber */
-        probability +=
-            0.01 * get_curseeffect(((ship *)obj)->attribs, C_RESIST_MAGIC, 0);
+        a = ((ship *)obj)->attribs;
         break;
     }
 
-    probability = MAX(0.02, probability + t_bonus * 0.01);
-    probability = MIN(0.98, probability);
+    if (a) {
+        const struct curse_type *ct_resist = ct_find(oldcursename(C_RESIST_MAGIC));
+        curse * c = get_curse(a, ct_resist);
+        int effect = curse_geteffect_int(c);
+        prob = frac_add(prob, frac_make(effect, 100));
+    }
+
+    /* ignore results < 2% and > 98% */
+    v02p = frac_make(1, 50);
+    v98p = frac_make(49, 50);
+    if (frac_sign(frac_sub(prob, v02p)) < 0) {
+        prob = v02p;
+    }
+    else if (frac_sign(frac_sub(prob, v98p)) > 0) {
+        prob = v98p;
+    }
 
     /* gibt true, wenn die Zufallszahl kleiner als die chance ist und
      * false, wenn sie gleich oder größer ist, dh je größer die
      * Magieresistenz (chance) desto eher gibt die Funktion true zurück */
-    return chance(probability);
+    return rng_int() % prob.sa[1] < prob.sa[0];
 }
 
 /* ------------------------------------------------------------- */
diff --git a/src/magic.h b/src/magic.h
index d282767a9..37fe33eae 100644
--- a/src/magic.h
+++ b/src/magic.h
@@ -315,7 +315,7 @@ extern "C" {
     bool is_magic_resistant(struct unit *magician, struct unit *target, int
         resist_bonus);
     /*      Mapperfunktion für target_resists_magic() vom Typ struct unit. */
-    extern double magic_resistance(struct unit *target);
+    variant magic_resistance(struct unit *target);
     /*      gibt die Chance an, mit der einem Zauber widerstanden wird. Je
      *      größer, desto resistenter ist da Opfer */
     bool target_resists_magic(struct unit *magician, void *obj, int objtyp,
diff --git a/src/magic.test.c b/src/magic.test.c
index baf8ede50..a5a842172 100644
--- a/src/magic.test.c
+++ b/src/magic.test.c
@@ -414,15 +414,15 @@ static void test_magic_resistance(CuTest *tc) {
     test_setup();
     rc = test_create_race("human");
     u = test_create_unit(test_create_faction(rc), test_create_region(0, 0, 0));
-    CuAssertDblEquals(tc, rc->magres/100.0, magic_resistance(u), 0.01);
-    rc->magres = 100;
-    CuAssertDblEquals_Msg(tc, "magic resistance is capped at 0.9", 0.9, magic_resistance(u), 0.01);
+    CuAssertTrue(tc, frac_equal(rc->magres, magic_resistance(u)));
+    rc->magres = frac_one;
+    CuAssert(tc, "magic resistance is capped at 0.9", frac_equal(magic_resistance(u), frac_make(9, 10)));
     rc = test_create_race("braineater");
-    rc->magres = 100;
+    rc->magres = frac_one;
     u_setrace(u, rc);
-    CuAssertDblEquals_Msg(tc, "brain eaters outside astral space have 50% magres", 0.5, magic_resistance(u), 0.01);
+    CuAssert(tc, "brain eaters outside astral space have 50% magres", frac_equal(magic_resistance(u), frac_make(1, 2)));
     u->region->_plane = get_astralplane();
-    CuAssertDblEquals_Msg(tc, "brain eaters in astral space have full magres", 0.9, magic_resistance(u), 0.01);
+    CuAssert(tc, "brain eaters in astral space have full magres", frac_equal(magic_resistance(u), frac_make(9, 10)));
     test_cleanup();
 }
 
diff --git a/src/spells.c b/src/spells.c
index 95b26434f..fcee1b51b 100644
--- a/src/spells.c
+++ b/src/spells.c
@@ -2851,7 +2851,8 @@ static int dc_age(struct curse *c)
         while (*up != NULL) {
             unit *u = *up;
             int hp;
-            double damage = c->effect * u->number;
+            variant dmg = frac_make(u->number, 1);
+            double damage = c->effect;
 
             if (u->number <= 0 || target_resists_magic(mage, u, TYP_UNIT, 0)) {
                 up = &u->next;
@@ -2859,7 +2860,9 @@ static int dc_age(struct curse *c)
             }
 
             /* Reduziert durch Magieresistenz */
-            damage *= (1.0 - magic_resistance(u));
+            dmg = frac_mul(dmg, frac_sub(frac_make(1,1), magic_resistance(u)));
+            damage *= dmg.sa[0];
+            damage /= dmg.sa[1];
             hp = change_hitpoints(u, -(int)damage);
 
             ADDMSG(&u->faction->msgs, msg_message((hp>0)?"poison_damage":"poison_death", "region unit", r, u));
diff --git a/src/spy.test.c b/src/spy.test.c
index 8341b17d3..ae1550689 100644
--- a/src/spy.test.c
+++ b/src/spy.test.c
@@ -71,7 +71,7 @@ static void test_all_spy_message(CuTest *tc) {
     set_factionstealth(fix.victim, fix.spy->faction);
 
     itype = it_get_or_create(rt_get_or_create("sword"));
-    new_weapontype(itype, 0, 0.0, NULL, 0, 0, 0, SK_MELEE, 2);
+    new_weapontype(itype, 0, frac_zero, NULL, 0, 0, 0, SK_MELEE, 2);
     i_change(&fix.victim->items, itype, 1);
 
     spy_message(99, fix.spy, fix.victim);
diff --git a/src/volcano.c b/src/volcano.c
index fb4cfa74c..9734bb2cd 100644
--- a/src/volcano.c
+++ b/src/volcano.c
@@ -80,7 +80,6 @@ damage_unit(unit * u, const char *dam, bool physical, bool magic)
     int *hp, hpstack[20];
     int h;
     int i, dead = 0, hp_rem = 0, heiltrank;
-    double magres = magic_resistance(u);
 
     assert(u->number);
     if (fval(u_race(u), RCF_ILLUSIONARY) || u_race(u) == get_race(RC_SPELL)) {
@@ -105,10 +104,14 @@ damage_unit(unit * u, const char *dam, bool physical, bool magic)
     /* Schaden */
     for (i = 0; i < u->number; i++) {
         int damage = dice_rand(dam);
-        if (magic)
-            damage = (int)(damage * (1.0 - magres));
-        if (physical)
+        if (magic) {
+            variant magres = magic_resistance(u);
+            magres = frac_sub(frac_make(1, 1), magres);
+            damage = damage * magres.sa[0] / magres.sa[1];
+        }
+        if (physical) {
             damage -= nb_armor(u, i);
+        }
         hp[i] -= damage;
     }