--- ./mozilla/memory/mozalloc/mozalloc.cpp.orig
+++ ./mozilla/memory/mozalloc/mozalloc.cpp
@@ -266,7 +266,7 @@
 
 #if defined(XP_MACOSX)
     return malloc_size(ptr);
-#elif defined(MOZ_MEMORY)
+#elif defined(MOZ_MEMORY) && !defined(__UCLIBC__)
     return malloc_usable_size(ptr);
 #elif defined(XP_WIN)
     return _msize(ptr);