diff --git a/objc/runtime.h b/objc/runtime.h
index 451ea3e..b2ee94d 100644
--- a/objc/runtime.h
+++ b/objc/runtime.h
@@ -328,6 +328,82 @@ static const id self = nil;
 
 #define objc_msgSendSuper(super, op, ...) objc_msg_lookup_super(super, op)((super)->receiver, op, ## __VA_ARGS__)
 
+/**
+ * Legacy GNU runtime compatibility.
+ *
+ * All of the functions in this section are deprecated and should not be used
+ * in new code.
+ */
+
+__attribute__((deprecated))
+void *objc_malloc(size_t size);
+
+__attribute__((deprecated))
+void *objc_atomic_malloc(size_t size);
+
+__attribute__((deprecated))
+void *objc_valloc(size_t size);
+
+__attribute__((deprecated))
+void *objc_realloc(void *mem, size_t size);
+
+__attribute__((deprecated))
+void * objc_calloc(size_t nelem, size_t size);
+
+__attribute__((deprecated))
+void objc_free(void *mem);
+
+__attribute__((deprecated))
+id objc_get_class(const char *name);
+
+__attribute__((deprecated))
+id objc_lookup_class(const char *name);
+
+__attribute__((deprecated))
+id objc_get_meta_class(const char *name);
+
+#if !defined(__OBJC_RUNTIME_INTERNAL__)
+__attribute__((deprecated))
+#endif
+Class objc_next_class(void **enum_state);
+
+__attribute__((deprecated))
+Class class_pose_as(Class impostor, Class super_class);
+
+__attribute__((deprecated))
+SEL sel_get_typed_uid (const char *name, const char *types);
+
+__attribute__((deprecated))
+SEL sel_get_any_typed_uid (const char *name);
+
+__attribute__((deprecated))
+SEL sel_get_any_uid (const char *name);
+
+__attribute__((deprecated))
+SEL sel_get_uid(const char *name);
+
+__attribute__((deprecated))
+const char *sel_get_name(SEL selector);
+
+#if !defined(__OBJC_RUNTIME_INTERNAL__)
+__attribute__((deprecated))
+#endif
+BOOL sel_is_mapped(SEL selector);
+
+__attribute__((deprecated))
+const char *sel_get_type(SEL selector);
+
+__attribute__((deprecated))
+SEL sel_register_name(const char *name);
+
+__attribute__((deprecated))
+SEL sel_register_typed_name(const char *name, const char *type);
+
+__attribute__((deprecated))
+BOOL sel_eq(SEL s1, SEL s2);
+
+
+
 #define _C_ID       '@'
 #define _C_CLASS    '#'
 #define _C_SEL      ':'
diff --git a/runtime.c b/runtime.c
index 702a3e8..39171cf 100644
--- a/runtime.c
+++ b/runtime.c
@@ -18,7 +18,6 @@
 #include <stdlib.h>
 #include <assert.h>
 
-Class objc_next_class(void*);
 struct objc_slot *objc_get_slot(Class cls, SEL selector);
 
 /**