diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index bfbba61bf2..d1a0f8d5b7 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -142,7 +142,7 @@ class Pathname
     return $1 if $1
 
     # eg foobar-4.5.0-bin
-    /-((\d+\.)+\d+[abc]?)[-.](bin|src|sources)$/.match stem
+    /-((\d+\.)+\d+[abc]?)[-.](bin|src|sources?)$/.match stem
     return $1 if $1
 
     # eg. otp_src_R13B (this is erlang's style)