diff --git a/src/attributes/object.h b/src/attributes/object.h
index 44bec8b56..b4d3f7870 100644
--- a/src/attributes/object.h
+++ b/src/attributes/object.h
@@ -21,7 +21,7 @@ extern "C" {
 
   typedef enum {
     TNONE = 0, TINTEGER = 1, TREAL = 2, TSTRING = 3,
-    TUNIT = 10, TFACTION = 11, TREGION = 12, TBUILDING = 13, TSHIP = 14,
+    TUNIT = 10, TFACTION = 11, TREGION = 12, TBUILDING = 13, TSHIP = 14
   } object_type;
 
   extern struct attrib_type at_object;
diff --git a/src/bindings/bind_attrib.c b/src/bindings/bind_attrib.c
index cdb2f0c6b..9e8d1a9c2 100644
--- a/src/bindings/bind_attrib.c
+++ b/src/bindings/bind_attrib.c
@@ -296,7 +296,7 @@ static int read_ext(attrib * a, void *owner, struct storage *store)
   a->data.v = 0;
   ur_add(data, a, resolve_bson);
   return AT_READ_OK;
-};
+}
 
 attrib_type at_lua_ext = {
   "lua", init_ext, free_ext, age_ext, write_ext, read_ext
diff --git a/src/bindings/bind_faction.c b/src/bindings/bind_faction.c
index c0ca97b8c..a9a181f78 100644
--- a/src/bindings/bind_faction.c
+++ b/src/bindings/bind_faction.c
@@ -69,7 +69,7 @@ int tolua_faction_add_item(lua_State * L)
     if (itype != NULL) {
       item *i = i_change(&self->items, itype, number);
       result = i ? i->number : 0;
-    }                           // if (itype!=NULL)
+    }                           /* if (itype!=NULL) */
   }
   lua_pushnumber(L, result);
   return 1;
diff --git a/src/bindings/bind_message.c b/src/bindings/bind_message.c
index cd7bcc8a7..ae27573d9 100644
--- a/src/bindings/bind_message.c
+++ b/src/bindings/bind_message.c
@@ -1,7 +1,7 @@
 #include <platform.h>
 #include <kernel/config.h>
 
-// kernel includes
+/* kernel includes */
 #include <kernel/faction.h>
 #include <kernel/item.h>
 #include <kernel/message.h>
@@ -9,10 +9,10 @@
 #include <kernel/region.h>
 #include <kernel/unit.h>
 
-// util includes
+/* util includes */
 #include <util/message.h>
 
-// lua includes
+/* lua includes */
 #include <lua.h>
 #include <tolua.h>
 
diff --git a/src/bindings/bind_unit.c b/src/bindings/bind_unit.c
index 8542d60c7..49c65d786 100644
--- a/src/bindings/bind_unit.c
+++ b/src/bindings/bind_unit.c
@@ -16,11 +16,11 @@ without prior permission by the authors of Eressea.
 #include "bind_attrib.h"
 #include "bindings.h"
 
-// attributes includes
+/*  attributes includes */
 #include <attributes/racename.h>
 #include <attributes/key.h>
 
-// kernel includes
+/*  kernel includes */
 #include <kernel/building.h>
 #include <kernel/config.h>
 #include <kernel/faction.h>
@@ -37,7 +37,7 @@ without prior permission by the authors of Eressea.
 #include <kernel/spell.h>
 #include <kernel/unit.h>
 
-// util includes
+/*  util includes */
 #include <util/attrib.h>
 #include <util/base36.h>
 #include <util/event.h>
@@ -937,7 +937,7 @@ void tolua_unit_open(lua_State * L)
       tolua_function(L, TOLUA_CAST "clear_orders", &tolua_unit_clear_orders);
       tolua_variable(L, TOLUA_CAST "orders", &tolua_unit_get_orders, 0);
 
-      // key-attributes for named flags:
+      /*  key-attributes for named flags: */
       tolua_function(L, TOLUA_CAST "set_flag", &tolua_unit_set_flag);
       tolua_function(L, TOLUA_CAST "get_flag", &tolua_unit_get_flag);
       tolua_variable(L, TOLUA_CAST "flags", &tolua_unit_get_flags,
@@ -945,21 +945,21 @@ void tolua_unit_open(lua_State * L)
       tolua_variable(L, TOLUA_CAST "age", &tolua_unit_get_age,
         tolua_unit_set_age);
 
-      // items:
+      /*  items: */
       tolua_function(L, TOLUA_CAST "get_item", &tolua_unit_get_item);
       tolua_function(L, TOLUA_CAST "add_item", &tolua_unit_add_item);
       tolua_variable(L, TOLUA_CAST "items", &tolua_unit_get_items, 0);
       tolua_function(L, TOLUA_CAST "get_pooled", &tolua_unit_get_pooled);
       tolua_function(L, TOLUA_CAST "use_pooled", &tolua_unit_use_pooled);
 
-      // skills:
+      /*  skills: */
       tolua_function(L, TOLUA_CAST "get_skill", &tolua_unit_getskill);
       tolua_function(L, TOLUA_CAST "eff_skill", &tolua_unit_effskill);
       tolua_function(L, TOLUA_CAST "set_skill", &tolua_unit_setskill);
 
       tolua_function(L, TOLUA_CAST "add_notice", &tolua_unit_addnotice);
 
-      // npc logic:
+      /*  npc logic: */
       tolua_function(L, TOLUA_CAST "add_handler", &tolua_unit_addhandler);
 
       tolua_variable(L, TOLUA_CAST "race_name", &tolua_unit_get_racename,
diff --git a/src/eressea.c b/src/eressea.c
index f1a9c1ab3..e637d2292 100644
--- a/src/eressea.c
+++ b/src/eressea.c
@@ -23,7 +23,7 @@
 #include <bindings/bind_ship.h>
 #include <bindings/bind_storage.h>
 #include <bindings/bind_unit.h>
-#endif // BINDINGS_TOLUA
+#endif /*  BINDINGS_TOLUA */
 
 #if MUSEUM_MODULE
 #include <modules/museum.h>
diff --git a/src/gamecode/laws.c b/src/gamecode/laws.c
index b9472dcf3..19dd3dbd6 100644
--- a/src/gamecode/laws.c
+++ b/src/gamecode/laws.c
@@ -731,7 +731,7 @@ static void
 growing_trees_e3(region * r, const int current_season,
   const int last_weeks_season)
 {
-  const static int transform[4][3] = {
+  static const int transform[4][3] = {
     {-1, -1, 0},
     {TREE_SEED, TREE_SAPLING, 2},
     {TREE_SAPLING, TREE_TREE, 2},
diff --git a/src/gamecode/report.c b/src/gamecode/report.c
index 1d64a60ba..5d635992d 100644
--- a/src/gamecode/report.c
+++ b/src/gamecode/report.c
@@ -2400,7 +2400,7 @@ report_plaintext(const char *filename, report_context * ctx,
           rnl(F);
           nr_paragraph(F, m, f);
         }
-        //
+        /*  */
       } else {
         if (!fval(r->terrain, SEA_REGION) && rpeasants(r) / TRADE_FRACTION > 0) {
           rnl(F);
diff --git a/src/gamecode/xmlreport.c b/src/gamecode/xmlreport.c
index afcb067eb..fc4666f37 100644
--- a/src/gamecode/xmlreport.c
+++ b/src/gamecode/xmlreport.c
@@ -754,7 +754,7 @@ static xmlNodePtr report_root(report_context * ctx)
       xmlAddChild(xmlReport, xml_region(ctx, sr));
   }
   return xmlReport;
-};
+}
 
 /* main function of the xmlreport. creates the header and traverses all regions */
 static int
diff --git a/src/kernel/alliance.c b/src/kernel/alliance.c
index f9e93637a..aca0c35a8 100644
--- a/src/kernel/alliance.c
+++ b/src/kernel/alliance.c
@@ -96,8 +96,8 @@ typedef struct alliance_transaction {
   struct alliance_transaction *next;
   unit *u;
   order *ord;
-//   alliance * al;
-//   variant userdata;
+/*    alliance * al; */
+/*    variant userdata; */
 } alliance_transaction;
 
 static struct alliance_transaction *transactions[ALLIANCE_MAX];
@@ -321,9 +321,9 @@ void alliance_cmd(void)
   if (stree == NULL) {
     syntaxtree *slang = stree = stree_create();
     while (slang) {
-      // struct tnode * root = calloc(sizeof(tnode), 1);
+      /*  struct tnode * root = calloc(sizeof(tnode), 1); */
       struct tnode *leaf = calloc(sizeof(tnode), 1);
-      // add_command(root, leaf, LOC(slang->lang, "alliance"), NULL);
+      /*  add_command(root, leaf, LOC(slang->lang, "alliance"), NULL); */
       add_command(leaf, NULL, LOC(slang->lang, "new"), &cmd_new);
       add_command(leaf, NULL, LOC(slang->lang, "invite"), &cmd_invite);
       add_command(leaf, NULL, LOC(slang->lang, "join"), &cmd_join);
diff --git a/src/kernel/item.c b/src/kernel/item.c
index 9f56280ea..72f21cac8 100644
--- a/src/kernel/item.c
+++ b/src/kernel/item.c
@@ -494,7 +494,9 @@ item *i_change(item ** pi, const item_type * itype, int delta)
     if (i->number < 0) {
       log_error(("serious accounting error. number of items is %d.\n",
           i->number));
+      /* FIXME what's this supposed to mean??
       assert(i >= 0);
+      */
       i->number = 0;
     }
     if (i->number == 0) {
diff --git a/src/kernel/magic.h b/src/kernel/magic.h
index 74cd5eb33..311024d54 100644
--- a/src/kernel/magic.h
+++ b/src/kernel/magic.h
@@ -53,7 +53,7 @@ extern "C" {
     SPP_BUILDING,               /*  -  : atoi() -> int */
     SPP_SHIP,                   /*  -  : atoi() -> int */
     SPP_STRING,                 /* "c" */
-    SPP_INT,                    /* "i" : atoi() -> int */
+    SPP_INT                     /* "i" : atoi() -> int */
   } sppobj_t;
 
   typedef struct spllprm {
diff --git a/src/kernel/reports.c b/src/kernel/reports.c
index 79cb31fa6..219660ca7 100644
--- a/src/kernel/reports.c
+++ b/src/kernel/reports.c
@@ -1141,7 +1141,7 @@ void seen_done(seen_region * seehash[])
     reuse = seehash[i];
     seehash[i] = NULL;
   }
-  // free(seehash);
+  /*  free(seehash); */
 }
 
 void free_seen(void)
diff --git a/src/kernel/skill.h b/src/kernel/skill.h
index 6cf79debf..8d91aab37 100644
--- a/src/kernel/skill.h
+++ b/src/kernel/skill.h
@@ -22,7 +22,7 @@ extern "C" {
 #define SMF_RIDING     (1<<2)   /* Bonus für berittene - an der rasse */
 
   typedef struct skill {
-    skill_t id:8;
+    unsigned int id:8;
     unsigned int level:8;
     unsigned int weeks:8;
     unsigned int old:8;
diff --git a/src/kernel/textstore.c b/src/kernel/textstore.c
index fe2fd251a..7c12d89be 100644
--- a/src/kernel/textstore.c
+++ b/src/kernel/textstore.c
@@ -135,7 +135,7 @@ static int txt_open(struct storage *store, const char *filename, int mode)
   FILE *F = fopen(filename, modes[mode]);
   store->userdata = F;
   if (F) {
-    const char utf8_bom[4] = { 0xef, 0xbb, 0xbf };
+    char utf8_bom[4] = { (char)0xef, (char)0xbb, (char)0xbf };
     if (mode == IO_READ) {
       char token[8];
       /* recognize UTF8 BOM */
diff --git a/src/kernel/xmlreader.c b/src/kernel/xmlreader.c
index c3cfd2de9..6cef9d00c 100644
--- a/src/kernel/xmlreader.c
+++ b/src/kernel/xmlreader.c
@@ -1869,9 +1869,9 @@ static int parse_races(xmlDocPtr doc)
       assert(propValue != NULL);
       frc = rc_find((const char *)propValue);
       if (frc == NULL) {
-//         log_error(("%s not registered, is familiar for %s\n",
-//           (const char*)propValue, rc->_name[0]));
-//         assert(frc!=NULL);
+/*          log_error(("%s not registered, is familiar for %s\n", */
+/*            (const char*)propValue, rc->_name[0])); */
+/*          assert(frc!=NULL); */
         frc = rc_add(rc_new((const char *)propValue));
       }
       if (xml_bvalue(node, "default", false)) {
diff --git a/src/platform.h b/src/platform.h
index cdf87ea37..b6d201040 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -16,6 +16,8 @@ ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 **/
 
+#define _GNU_SOURCE
+
 #ifndef CONFIG_H
 #define CONFIG_H
 
diff --git a/src/util/strings.c b/src/util/strings.c
index 94e0577f8..ade70fe35 100644
--- a/src/util/strings.c
+++ b/src/util/strings.c
@@ -51,7 +51,7 @@ escape_string_inplace(char * buffer, unsigned int len, unsigned int offset)
   }
   d[i] = o;
   if (i<MAXQUOTES) {
-    // more than 32 hits! must go recursive
+    //  more than 32 hits! must go recursive
     char * start = d[i];
     unsigned int nlen = len - (start-buffer) - MAXQUOTES;
     escape_string_inplace(start, nlen, MAXQUOTES);
@@ -121,11 +121,11 @@ INLINE_FUNCTION unsigned int jenkins_hash(unsigned int a)
 
 INLINE_FUNCTION unsigned int wang_hash(unsigned int a)
 {
-  a = ~a + (a << 15);           // a = (a << 15) - a - 1;
+  a = ~a + (a << 15);           /*  a = (a << 15) - a - 1; */
   a = a ^ (a >> 12);
   a = a + (a << 2);
   a = a ^ (a >> 4);
-  a = a * 2057;                 // a = (a + (a << 3)) + (a << 11);
+  a = a * 2057;                 /*  a = (a + (a << 3)) + (a << 11); */
   a = a ^ (a >> 16);
   return a;
 }
diff --git a/src/util/unicode.c b/src/util/unicode.c
index e15aa44f3..ca7d0fbad 100644
--- a/src/util/unicode.c
+++ b/src/util/unicode.c
@@ -81,12 +81,12 @@ unicode_latin1_to_utf8(utf8_t * out, size_t * outlen, const char *in,
     if (c > 0xBF) {
       if (op - out >= os - 1)
         break;
-      *op++ = 0xC3;
+      *op++ = (char) 0xC3;
       *op++ = c - 64;
     } else if (c > 0x7F) {
       if (op - out >= os - 1)
         break;
-      *op++ = 0xC2;
+      *op++ = (char) 0xC2;
       *op++ = c;
     } else {
       if (op - out >= os)
diff --git a/src/util/xml.c b/src/util/xml.c
index de9aa0cd1..cd1878206 100644
--- a/src/util/xml.c
+++ b/src/util/xml.c
@@ -28,7 +28,7 @@
 const xmlChar *xml_i(double number)
 {
   static char buffer[128];
-  snprintf(buffer, sizeof(buffer), "%.0lf", number);
+  snprintf(buffer, sizeof(buffer), "%.0f", number);
   return (const xmlChar *)buffer;
 }