diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index efd7e36535..01e87c5d64 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -127,44 +127,44 @@ class Version
     return m.captures.first unless m.nil?
 
     # e.g. https://github.com/erlang/otp/tarball/OTP_R15B01 (erlang style)
-    m = /[-_](R\d+[AB]\d*(-\d+)?)/.match(spec_s)
+    m = /[-_](R\d+[AB]\d*(?:-\d+)?)/.match(spec_s)
     return m.captures.first unless m.nil?
 
     # e.g. boost_1_39_0
-    m = /((\d+_)+\d+)$/.match(stem)
+    m = /((?:\d+_)+\d+)$/.match(stem)
     return m.captures.first.gsub('_', '.') unless m.nil?
 
     # e.g. foobar-4.5.1-1
     # e.g. ruby-1.9.1-p243
-    m = /-((\d+\.)*\d\.\d+-(p|rc|RC)?\d+)(?:[-._](?:bin|dist|stable|src|sources))?$/.match(stem)
+    m = /-((?:\d+\.)*\d\.\d+-(?:p|rc|RC)?\d+)(?:[-._](?:bin|dist|stable|src|sources))?$/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. lame-398-1
-    m = /-((\d)+-\d)/.match(stem)
+    m = /-((?:\d)+-\d)/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. foobar-4.5.1
-    m = /-((\d+\.)*\d+)$/.match(stem)
+    m = /-((?:\d+\.)*\d+)$/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. foobar-4.5.1b
-    m = /-((\d+\.)*\d+([abc]|rc|RC)\d*)$/.match(stem)
+    m = /-((?:\d+\.)*\d+(?:[abc]|rc|RC)\d*)$/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. foobar-4.5.0-beta1, or foobar-4.50-beta
-    m = /-((\d+\.)*\d+-beta(\d+)?)$/.match(stem)
+    m = /-((?:\d+\.)*\d+-beta\d*)$/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. foobar4.5.1
-    m = /((\d+\.)*\d+)$/.match(stem)
+    m = /((?:\d+\.)*\d+)$/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. foobar-4.5.0-bin
-    m = /-((\d+\.)+\d+[abc]?)[-._](bin|dist|stable|src|sources?)$/.match(stem)
+    m = /-((?:\d+\.)+\d+[abc]?)[-._](?:bin|dist|stable|src|sources?)$/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. dash_0.5.5.1.orig.tar.gz (Debian style)
-    m = /_((\d+\.)+\d+[abc]?)[.]orig$/.match(stem)
+    m = /_((?:\d+\.)+\d+[abc]?)[.]orig$/.match(stem)
     return m.captures.first unless m.nil?
 
     # e.g. http://www.openssl.org/source/openssl-0.9.8s.tar.gz