Index: src/game/bg_lib.h
===================================================================
--- src/game/bg_lib.h	(revision 1090)
+++ src/game/bg_lib.h	(working copy)
@@ -76,6 +76,16 @@
 void        qsort( void *a, size_t n, size_t es, cmp_t *cmp );
 void        srand( unsigned seed );
 int         rand( void );
+// FIXME: NDEBUG isn't defined for compiling the QVMs
+#ifndef NDEBUG
+// these two are so that __LINE__ is expanded and *then* strung
+#define str2(x) #x
+#define str(x) str2(x)
+#define assert( x ) if( !( x ) ) Com_Error( ERR_DROP, \
+    __FILE__ ":" str(__LINE__) ": Assertion `" #x "' failed" );
+#else
+#define assert( x ) // nothing
+#endif
 
 // String functions
 size_t  strlen( const char *string );