Index: uspace/lib/c/include/malloc.h
===================================================================
--- uspace/lib/c/include/malloc.h	(revision 8a64320e304a59746f5987caeba986e6baf11dd7)
+++ uspace/lib/c/include/malloc.h	(revision 7ec3c5638215716bb0cffafe64b4b0bdc6a543b3)
@@ -44,5 +44,6 @@
 extern void *memalign(const size_t align, const size_t size)
     __attribute__((malloc));
-extern void *realloc(const void *addr, const size_t size);
+extern void *realloc(const void *addr, const size_t size)
+    __attribute__((warn_unused_result));
 extern void free(const void *addr);
 extern void *heap_check(void);
Index: uspace/lib/c/include/mem.h
===================================================================
--- uspace/lib/c/include/mem.h	(revision 8a64320e304a59746f5987caeba986e6baf11dd7)
+++ uspace/lib/c/include/mem.h	(revision 7ec3c5638215716bb0cffafe64b4b0bdc6a543b3)
@@ -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
Index: uspace/lib/c/include/task.h
===================================================================
--- uspace/lib/c/include/task.h	(revision 8a64320e304a59746f5987caeba986e6baf11dd7)
+++ uspace/lib/c/include/task.h	(revision 7ec3c5638215716bb0cffafe64b4b0bdc6a543b3)
@@ -60,5 +60,6 @@
 extern int task_spawn(task_id_t *, task_wait_t *, const char *path, int,
     va_list ap);
-extern int task_spawnl(task_id_t *, task_wait_t *, const char *path, ...);
+extern int task_spawnl(task_id_t *, task_wait_t *, const char *path, ...)
+    __attribute__((sentinel));
 
 extern int task_setup_wait(task_id_t, task_wait_t *);