diff --git a/spec/runtime/helpers/spy_reader.cc b/spec/runtime/helpers/spy_reader.cc
index e7f38f49..1af08a5e 100644
--- a/spec/runtime/helpers/spy_reader.cc
+++ b/spec/runtime/helpers/spy_reader.cc
@@ -1,4 +1,5 @@
 #include "runtime/helpers/spy_reader.h"
+#include <string.h>
 #include <algorithm>
 
 using std::string;