diff --git a/reploy.hs b/reploy.hs
index 3d934f3..12d7a57 100644
--- a/reploy.hs
+++ b/reploy.hs
@@ -192,7 +192,7 @@ checkedSubstitute :: Mu.Template -> MT.Value -> IO T.Text
 checkedSubstitute t v = do
   let (es, txt) = Mu.checkedSubstitute t v
   traverse_ (putStrLn . ("Error: " ++) . show) es
-  --null es `unless` error "template substitution problems!"
+  null es `unless` error "template substitution problems!"
   pure txt
 
 -- | Add global information to page metadata for rendering (at this point just the url base)