diff --git a/clay.cabal b/clay.cabal
--- a/clay.cabal
+++ b/clay.cabal
@@ -1,5 +1,5 @@
 Name:     clay
-Version:  0.5
+Version:  0.5.1
 Synopsis: CSS preprocessor as embedded Haskell.
 Description:
   Clay is a CSS preprocessor like LESS and Sass, but implemented as an embedded
@@ -11,9 +11,8 @@
   .
   The API documentation can be found in the top level module "Clay".
   .
-  > 0.4 -> 0.5
-  >   - Generalized the borderRadius function.
-  >   - Fixed some small issues in Dynamic.
+  > 0.5 -> 0.5.1
+  >   - Fixed bug in fontFamily renderer.
 
 Author:        Sebastiaan Visser
 Maintainer:    Sebastiaan Visser <code@fvisser.nl>
diff --git a/src/Clay/Font.hs b/src/Clay/Font.hs
--- a/src/Clay/Font.hs
+++ b/src/Clay/Font.hs
@@ -118,7 +118,9 @@
 -------------------------------------------------------------------------------
 
 fontFamily :: [Text] -> [Text] -> Css
-fontFamily a b = key "font-family" (value (Literal <$> a) <> if null b then "" else (", " <> value b))
+fontFamily a b = key "font-family" $
+  let sep = if null a || null b then "" else ", "
+   in value (Literal <$> a) <> sep <> value b
 
 sansSerif :: Text
 sansSerif = "sans-serif"