diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index 2cd6db0448..337afbfc97 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -202,16 +202,18 @@ class Pathname
   end
 
   def compression_type
-    # Don't treat jars or wars as compressed
-    return nil if self.extname == '.jar'
-    return nil if self.extname == '.war'
-
-    # OS X installer package
-    return :pkg if self.extname == '.pkg'
-
-    # If the filename ends with .gz not preceded by .tar
-    # then we want to gunzip but not tar
-    return :gzip_only if self.extname == '.gz'
+    case extname
+    when ".jar", ".war"
+      # Don't treat jars or wars as compressed
+      return
+    when ".pkg"
+      # OS X installer package
+      return :pkg
+    when ".gz"
+      # If the filename ends with .gz not preceded by .tar
+      # then we want to gunzip but not tar
+      return :gzip_only
+    end
 
     # Get enough of the file to detect common file types
     # POSIX tar magic has a 257 byte offset