Index: uspace/lib/c/include/mem.h
===================================================================
--- uspace/lib/c/include/mem.h	(revision 797d4d193fb13a383f79845727e8ac92d9d83ae6)
+++ uspace/lib/c/include/mem.h	(revision 9191607440bc0b0a26066f644078cb7668d5529d)
@@ -40,9 +40,13 @@
 
 extern void *memset(void *, int, size_t)
+    __attribute__((nonnull(1)))
     ATTRIBUTE_OPTIMIZE("-fno-tree-loop-distribute-patterns");
 extern void *memcpy(void *, const void *, size_t)
+    __attribute__((nonnull(1, 2)))
     ATTRIBUTE_OPTIMIZE("-fno-tree-loop-distribute-patterns");
-extern void *memmove(void *, const void *, size_t);
-extern int memcmp(const void *, const void *, size_t);
+extern void *memmove(void *, const void *, size_t)
+    __attribute__((nonnull(1, 2)));
+extern int memcmp(const void *, const void *, size_t)
+    __attribute__((nonnull(1, 2)));
 
 #endif