diff --git a/libc/include/malloc.h b/libc/include/malloc.h
index eaedc49..9a4e324 100644
--- a/libc/include/malloc.h
+++ b/libc/include/malloc.h
@@ -27,16 +27,16 @@
 
 __BEGIN_DECLS
 
-extern void* malloc(size_t byte_count) __mallocfunc __wur;
-extern void* calloc(size_t item_count, size_t item_size) __mallocfunc __wur;
-extern void* realloc(void* p, size_t byte_count) __wur;
+extern void* malloc(size_t byte_count) __mallocfunc __wur __attribute__((alloc_size(1)));
+extern void* calloc(size_t item_count, size_t item_size) __mallocfunc __wur __attribute__((alloc_size(1,2)));
+extern void* realloc(void* p, size_t byte_count) __wur __attribute__((alloc_size(2)));
 extern void free(void* p);
 
-extern void* memalign(size_t alignment, size_t byte_count) __mallocfunc __wur;
+extern void* memalign(size_t alignment, size_t byte_count) __mallocfunc __wur __attribute__((alloc_size(2)));
 extern size_t malloc_usable_size(const void* p);
 
-extern void* valloc(size_t byte_count) __mallocfunc __wur;
-extern void* pvalloc(size_t byte_count) __mallocfunc __wur;
+extern void* valloc(size_t byte_count) __mallocfunc __wur __attribute__((alloc_size(1)));
+extern void* pvalloc(size_t byte_count) __mallocfunc __wur __attribute__((alloc_size(1)));
 
 #ifndef STRUCT_MALLINFO_DECLARED
 #define STRUCT_MALLINFO_DECLARED 1