diff --git a/HakyllBibTex.hs b/HakyllBibTex.hs
index 9543a71..1f9b672 100644
--- a/HakyllBibTex.hs
+++ b/HakyllBibTex.hs
@@ -113,6 +113,7 @@ expandMonth mon = case mon of
     "oct" -> "October"
     "nov" -> "November"
     "dec" -> "December"
+    x     -> x
 
 --------------------------------------------------------------------------------
 -- Inefficient...