@@ -361,19 +361,27 @@
 #endif
 
 #define OF_RETAIN_COUNT_MAX UINT_MAX
 #define OF_NOT_FOUND SIZE_MAX
 
-#define OF_ENSURE(cond)							\
+#ifdef OBJC_COMPILING_RUNTIME
+# define OF_ENSURE(cond)						   \
+	do {								   \
+		if OF_UNLIKELY (!(cond))				   \
+			OBJC_ERROR("Failed to ensure condition:\n" #cond); \
+	} while(0)
+#else
+# define OF_ENSURE(cond)						\
 	do {								\
-		if (!(cond)) {						\
+		if OF_UNLIKELY (!(cond)) {				\
 			fprintf(stderr, "Failed to ensure condition "	\
 			    "in " __FILE__ ":%d:\n" #cond "\n",		\
 			    __LINE__);					\
 			abort();					\
 		}							\
 	} while (0)
+#endif
 
 #define OF_UNRECOGNIZED_SELECTOR of_method_not_found(self, _cmd);
 #if __has_feature(objc_arc)
 # define OF_INVALID_INIT_METHOD of_method_not_found(self, _cmd);
 #else