diff --git a/ext/libzip/zip_source_file_win32_utf8.c b/ext/libzip/zip_source_file_win32_utf8.c
index 4f258bc411..4955eede2d 100644
--- a/ext/libzip/zip_source_file_win32_utf8.c
+++ b/ext/libzip/zip_source_file_win32_utf8.c
@@ -31,6 +31,7 @@
   IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+#include <stdlib.h>
 #include "zip_source_file_win32.h"
 
 ZIP_EXTERN zip_source_t *