diff --git a/src/bindings.c b/src/bindings.c
index 3024b2311..b2db9d761 100755
--- a/src/bindings.c
+++ b/src/bindings.c
@@ -394,10 +394,10 @@ static int tolua_learn_skill(lua_State * L)
 {
     unit *u = (unit *)tolua_tousertype(L, 1, 0);
     const char *skname = tolua_tostring(L, 2, 0);
-    float chances = (float)tolua_tonumber(L, 3, 0);
+    int days = (int)tolua_tonumber(L, 3, 0);
     skill_t sk = findskill(skname);
     if (sk != NOSKILL) {
-        learn_skill_depr(u, sk, chances);
+        learn_skill(u, sk, days);
     }
     return 0;
 }
@@ -1119,7 +1119,7 @@ int tolua_bindings_open(lua_State * L)
         tolua_function(L, TOLUA_CAST "update_subscriptions", tolua_update_subscriptions);
         tolua_function(L, TOLUA_CAST "update_scores", tolua_update_scores);
         tolua_function(L, TOLUA_CAST "update_owners", tolua_update_owners);
-        tolua_function(L, TOLUA_CAST "learn_skill_depr", tolua_learn_skill);
+        tolua_function(L, TOLUA_CAST "learn_skill", tolua_learn_skill);
         tolua_function(L, TOLUA_CAST "create_curse", tolua_create_curse);
         tolua_function(L, TOLUA_CAST "autoseed", tolua_autoseed);
         tolua_function(L, TOLUA_CAST "get_key", tolua_getkey);
diff --git a/src/items/xerewards.c b/src/items/xerewards.c
index 1563810d6..98e099070 100644
--- a/src/items/xerewards.c
+++ b/src/items/xerewards.c
@@ -53,9 +53,7 @@ struct order *ord)
     for (n = 0; n != amount; ++n) {
         skill *sv = u->skills;
         while (sv != u->skills + u->skill_size) {
-            int i;
-            for (i = 0; i != 3; ++i)
-                learn_skill_depr(u, (skill_t)sv->id, 1.0);
+            learn_skill(u, (skill_t)sv->id, STUDYDAYS * 3);
             ++sv;
         }
     }
diff --git a/src/items/xerewards.test.c b/src/items/xerewards.test.c
index cd620f039..ea9f53fde 100644
--- a/src/items/xerewards.test.c
+++ b/src/items/xerewards.test.c
@@ -31,17 +31,17 @@ static void test_skillpotion(CuTest *tc) {
     itype = test_create_itemtype("skillpotion");
     change_resource(u, itype->rtype, 2);
 
-    learn_skill_depr(u, SK_ENTERTAINMENT, 1.0);
+    learn_skill(u, SK_ENTERTAINMENT, STUDYDAYS);
     pSkill = unit_skill(u, SK_ENTERTAINMENT);
     sk_set(pSkill, 5);
     initialWeeks_Entertainment = pSkill->weeks = 4;
 
-    learn_skill_depr(u, SK_STAMINA, 1.0);
+    learn_skill(u, SK_STAMINA, STUDYDAYS);
     pSkill = unit_skill(u, SK_STAMINA);
     sk_set(pSkill, 5);
     initialWeeks_Stamina = pSkill->weeks = 4;
 
-    learn_skill_depr(u, SK_MAGIC, 1.0);
+    learn_skill(u, SK_MAGIC, STUDYDAYS);
     pSkill = unit_skill(u, SK_MAGIC);
     sk_set(pSkill, 5);
     initialWeeks_Magic = pSkill->weeks = 4;
diff --git a/src/kernel/skills.c b/src/kernel/skills.c
index cb0dcddea..171d42dd0 100644
--- a/src/kernel/skills.c
+++ b/src/kernel/skills.c
@@ -206,7 +206,7 @@ int level(int days)
 
 void sk_set(skill * sv, int level)
 {
-    assert(level != 0);
+    assert(sv && level != 0);
     sv->weeks = skill_weeks(level);
     sv->level = level;
 }
diff --git a/src/randenc.c b/src/randenc.c
index dfa1e998d..6a642557b 100644
--- a/src/randenc.c
+++ b/src/randenc.c
@@ -151,22 +151,17 @@ static void dissolve_units(void)
     remove_empty_units();
 }
 
-static int improve_all(faction * f, skill_t sk, int by_weeks)
+static bool improve_all(faction * f, skill_t sk, int by_weeks)
 {
     unit *u;
-    bool ret = by_weeks;
-
+    bool result = false;
     for (u = f->units; u; u = u->nextF) {
         if (has_skill(u, sk)) {
-            int weeks = 0;
-            for (; weeks != by_weeks; ++weeks) {
-                learn_skill_depr(u, sk, 1.0);
-                ret = 0;
-            }
+            learn_skill(u, sk, by_weeks * STUDYDAYS);
+            result = true;
         }
     }
-
-    return ret;
+    return result;
 }
 
 void find_manual(region * r, unit * u)
@@ -247,10 +242,8 @@ void find_manual(region * r, unit * u)
         msg_release(msg);
     }
 
-    if (improve_all(u->faction, skill, 3) == 3) {
-        int i;
-        for (i = 0; i != 9; ++i)
-            learn_skill_depr(u, skill, 1.0);
+    if (!improve_all(u->faction, skill, 3)) {
+        learn_skill(u, skill, 9 * STUDYDAYS);
     }
 }
 
diff --git a/src/study.c b/src/study.c
index aeb27b89d..af58a1f52 100644
--- a/src/study.c
+++ b/src/study.c
@@ -847,7 +847,6 @@ bool learn_skill_depr(unit * u, skill_t sk, double learn_chance)
 }
 
 void learn_skill(unit *u, skill_t sk, int days) {
-    skill *sv = u->skills;
     int leveldays = STUDYDAYS * u->number;
     int weeks = 0;
     while (days >= leveldays) {
@@ -857,14 +856,17 @@ void learn_skill(unit *u, skill_t sk, int days) {
     if (days > 0 && rng_int() % leveldays < days) {
         ++weeks;
     }
-    if (weeks > 0 && !sv) {
-        sv = add_skill(u, sk);
+    if (weeks > 0) {
+        skill *sv = unit_skill(u, sk);
+        if (!sv) {
+            sv = add_skill(u, sk);
+        }
+        while (sv->weeks <= weeks) {
+            weeks -= sv->weeks;
+            sk_set(sv, sv->level + 1);
+        }
+        sv->weeks -= weeks;
     }
-    while (sv->weeks <= weeks) {
-        weeks -= sv->weeks;
-        sk_set(sv, sv->level + 1);
-    }
-    sv->weeks -= weeks;
 }
 
 /** Talente von Dämonen verschieben sich.