diff --git a/tools/scratch.cpp b/tools/scratch.cpp
index 8d0cd357..1af75a8c 100644
--- a/tools/scratch.cpp
+++ b/tools/scratch.cpp
@@ -1,4 +1,5 @@
 #include <cstdlib>
+#include <iostream>
 
 int
 main (int argc, char **argv)