diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index e5ce553418..d7d3e5edf8 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -8,7 +8,7 @@
 #include <unistd.h>
 #include <signal.h>
 
-#include <iostream>
+#include <cstdio>
 
 
 namespace nix {