diff --git a/Source/kwsys/testProcess.c b/Source/kwsys/testProcess.c
index ef04268b3e..fb0916f69a 100644
--- a/Source/kwsys/testProcess.c
+++ b/Source/kwsys/testProcess.c
@@ -14,6 +14,7 @@
 #include <kwsys/Process.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #if defined(_WIN32)
 # include <windows.h>