--- a/dmlib.h	Thu Oct 11 16:01:14 2012 +0300
+++ b/dmlib.h	Thu Oct 11 16:04:02 2012 +0300
@@ -71,14 +71,6 @@
 #define DMRES_RES_FILE  "res.txt"   // Resource data file
 
 
-// Mutexes
-#define DMMutex SDL_mutex
-#define dmCreateMutex() SDL_CreateMutex()
-#define dmDestroyMutex(x) SDL_DestroyMutex(x)
-#define dmMutexLock(x) SDL_mutexP(x)
-#define dmMutexUnlock(x) SDL_mutexV(x)
-
-
 /* Define a boolean type
  */
 #if !defined(FALSE) && !defined(TRUE) && !defined(BOOL)
@@ -381,6 +373,42 @@
 char *     dm_strdup_printf(const char *, ...);
 
 
+/* Mutexes
+ */
+#ifdef DM_MUTEX_DEBUG
+
+typedef struct
+{
+    BOOL used;
+    Uint32 id;
+    int state;
+} DMMutexLock;
+
+typedef struct
+{
+    char *cr_file;
+    int cr_line;
+    SDL_mutex *m;
+    DMMutexLock locks[8];
+} DMMutex;
+
+#define dmMutexLock(x) dmDOMutexLock(x, __FILE__, (int) __LINE__)
+#define dmMutexUnlock(x) dmDOMutexUnlock(x, __FILE__, (int) __LINE__)
+#define dmCreateMutex(x) dmDOCreateMutex(__FILE__, (int) __LINE__)
+
+int        dmDOMutexLock(DMMutex *mutex, const char *file, const int line);
+int        dmDOMutexUnlock(DMMutex *mutex, const char *file, const int line);
+DMMutex *  dmDOCreateMutex(const char *file, const int line);
+void       dmDestroyMutex(DMMutex *mutex);
+
+#else
+#define DMMutex SDL_mutex
+#define dmCreateMutex() SDL_CreateMutex()
+#define dmDestroyMutex(x) SDL_DestroyMutex(x)
+#define dmMutexLock(x) SDL_mutexP(x)
+#define dmMutexUnlock(x) SDL_mutexV(x)
+#endif
+
 /* Endianess swapping macros
  */
 #define DM_SWAP_16_LE_BE(value)    ((Uint16) (   \