diff --git a/libutils/include/utils/Flattenable.h b/libutils/include/utils/Flattenable.h
index 953b85988..17c5e1057 100644
--- a/libutils/include/utils/Flattenable.h
+++ b/libutils/include/utils/Flattenable.h
@@ -52,7 +52,12 @@ public:
 
     template<size_t N>
     static size_t align(void*& buffer) {
-        return align<N>( const_cast<void const*&>(buffer) );
+        static_assert(!(N & (N - 1)), "Can only align to a power of 2.");
+        void* b = buffer;
+        buffer = reinterpret_cast<void*>((uintptr_t(buffer) + (N-1)) & ~(N-1));
+        size_t delta = size_t(uintptr_t(buffer) - uintptr_t(b));
+        memset(b, 0, delta);
+        return delta;
     }
 
     static void advance(void*& buffer, size_t& size, size_t offset) {