diff --git a/Tests/StringFileTest/StringFile.cxx b/Tests/StringFileTest/StringFile.cxx
index 6c3a7e3311..bc2312be0b 100644
--- a/Tests/StringFileTest/StringFile.cxx
+++ b/Tests/StringFileTest/StringFile.cxx
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <string.h>
 #include "OutputFile.h"
 
 int main(int, char*[])