diff --git a/ssl/test/async_bio.cc b/ssl/test/async_bio.cc
index 88f8e9a..c007ffa 100644
--- a/ssl/test/async_bio.cc
+++ b/ssl/test/async_bio.cc
@@ -15,8 +15,11 @@
 #include "async_bio.h"
 
 #include <errno.h>
+#include <string.h>
+
 #include <openssl/mem.h>
 
+
 namespace {
 
 extern const BIO_METHOD async_bio_method;