diff --git a/ext/vjson/block_allocator.cpp b/ext/vjson/block_allocator.cpp
index 16f3c4f9ec..f85de3a5ba 100644
--- a/ext/vjson/block_allocator.cpp
+++ b/ext/vjson/block_allocator.cpp
@@ -1,5 +1,6 @@
 #include <memory.h>
 #include <algorithm>
+#include <stdlib.h>
 #include "block_allocator.h"
 
 block_allocator::block_allocator(size_t blocksize)