diff --git a/test/WriteFile.cxx b/test/WriteFile.cxx
index a281d379d..307d89c61 100644
--- a/test/WriteFile.cxx
+++ b/test/WriteFile.cxx
@@ -27,6 +27,7 @@
 
 #include <string.h>
 #include <stdlib.h>
+#include <stdio.h>
 
 static bool
 Copy(OutputStream &dest, int src)