diff --git a/src/core/IO.pm b/src/core/IO.pm
index 33e708a8681..5975409f88b 100644
--- a/src/core/IO.pm
+++ b/src/core/IO.pm
@@ -44,7 +44,7 @@ class IO {
     }
 
     multi method printf($format, *@args) {
-#        self.print(sprintf($format, |@args));
+        self.print(sprintf($format, |@args));
     }
 
     multi method say(*@items) {
@@ -131,4 +131,9 @@ multi lines (Str $filename, Any  $limit = *) {
     $fh.lines($limit);
 }
 
+multi sub printf($format, *@args) {
+    $*OUT.printf($format, |@args);
+
+}
+
 # vim: ft=perl6