diff --git a/xpcom/ds/nsSupportsArray.cpp b/xpcom/ds/nsSupportsArray.cpp
index e9a9564bde1f..02e041e46316 100644
--- a/xpcom/ds/nsSupportsArray.cpp
+++ b/xpcom/ds/nsSupportsArray.cpp
@@ -18,6 +18,7 @@
 
 #include "nsSupportsArray.h"
 #include "nsSupportsArrayEnumerator.h"
+#include <string.h>
 
 static const PRUint32 kGrowArrayBy = 8;