diff --git a/crypto/test/file_test.cc b/crypto/test/file_test.cc
index 12405f2..8df6f9a 100644
--- a/crypto/test/file_test.cc
+++ b/crypto/test/file_test.cc
@@ -17,6 +17,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <stdarg.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include <openssl/err.h>