--- a/MIMETypes.st	Fri Jul 24 13:20:00 2015 +0200
+++ b/MIMETypes.st	Wed Jul 29 13:07:27 2015 +0200
@@ -1361,12 +1361,12 @@
     commentSpec notNil ifTrue:[
         ^ commentSpec
     ].
-
-    commentSpec := SuffixToCommentStringMapping at:suff ifAbsent:nil.
-    commentSpec notNil ifTrue:[
-        ^ commentSpec
+    suff notNil ifTrue:[
+        commentSpec := SuffixToCommentStringMapping at:suff ifAbsent:nil.
+        commentSpec notNil ifTrue:[
+            ^ commentSpec
+        ].
     ].
-
     ^ alternativeBlockReturningCommentString value
 
     "