diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index 8398bb17d0..54435aa372 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -157,7 +157,7 @@ class Pathname
     return $1 if $1
 
     # eg foobar-4.5.0-bin
-    /-((\d+\.)+\d+[abc]?)[-.](bin|stable|src|sources?)$/.match stem
+    /-((\d+\.)+\d+[abc]?)[-._](bin|stable|src|sources?)$/.match stem
     return $1 if $1
 
     # Debian style eg dash_0.5.5.1.orig.tar.gz