diff --git a/Library/Homebrew/cmd/tap.rb b/Library/Homebrew/cmd/tap.rb
index 15ebacb613..b24c70e87e 100644
--- a/Library/Homebrew/cmd/tap.rb
+++ b/Library/Homebrew/cmd/tap.rb
@@ -107,7 +107,7 @@ module Homebrew extend self
   end
 
   def tap_args
-    ARGV.first =~ %r{^([\w_-]+)/(homebrew-)?([\w_-]+)$}
+    ARGV.first =~ %r{^([\w-]+)/(homebrew-)?([\w-]+)$}
     raise "Invalid tap name" unless $1 && $3
     [$1, $3]
   end
@@ -122,7 +122,7 @@ module Homebrew extend self
 
   def tap_ref(path)
     case path.to_s
-    when %r{^#{HOMEBREW_LIBRARY}/Taps/([\w_-]+)/([\w_-]+)/(.+)}
+    when %r{^#{HOMEBREW_LIBRARY}/Taps/([\w-]+)/([\w-]+)/(.+)}
       "#$1/#$2/#{File.basename($3, '.rb')}"
     when %r{^#{HOMEBREW_LIBRARY}/Formula/(.+)}
       "Homebrew/homebrew/#{File.basename($1, '.rb')}"
diff --git a/Library/Homebrew/cmd/update.rb b/Library/Homebrew/cmd/update.rb
index f89207966d..45f8251baf 100644
--- a/Library/Homebrew/cmd/update.rb
+++ b/Library/Homebrew/cmd/update.rb
@@ -219,7 +219,7 @@ class Report < Hash
   def tapped_formula_for key
     fetch(key, []).select do |path|
       case path.relative_path_from(HOMEBREW_REPOSITORY).to_s
-      when %r{^Library/Taps/([\w_-]+/[\w_-]+/.*)}
+      when %r{^Library/Taps/([\w-]+/[\w-]+/.*)}
         valid_formula_location?($1)
       else
         false
@@ -250,7 +250,7 @@ class Report < Hash
       case path.relative_path_from(HOMEBREW_REPOSITORY).to_s
       when %r{^Library/Formula}
         path.basename(".rb").to_s
-      when %r{^Library/Taps/([\w_-]+)/(homebrew-)?([\w_-]+)/(.*)\.rb}
+      when %r{^Library/Taps/([\w-]+)/(homebrew-)?([\w-]+)/(.*)\.rb}
         "#$1/#$3/#{path.basename(".rb")}"
       end
     end.compact.sort
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index 2a001256ee..5e44461965 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -85,8 +85,8 @@ HOMEBREW_USER_AGENT = "Homebrew #{HOMEBREW_VERSION} (Ruby #{RUBY_VERSION}-#{RUBY
 
 HOMEBREW_CURL_ARGS = '-f#LA'
 
-HOMEBREW_TAP_FORMULA_REGEX = %r{^([\w_-]+)/([\w_-]+)/([\w_-]+)$}
-HOMEBREW_TAP_DIR_REGEX = %r{#{HOMEBREW_LIBRARY}/Taps/([\w_-]+)/([\w_-]+)}
+HOMEBREW_TAP_FORMULA_REGEX = %r{^([\w-]+)/([\w-]+)/([\w-]+)$}
+HOMEBREW_TAP_DIR_REGEX = %r{#{HOMEBREW_LIBRARY}/Taps/([\w-]+)/([\w-]+)}
 HOMEBREW_TAP_PATH_REGEX = Regexp.new(HOMEBREW_TAP_DIR_REGEX.source \
                                      + %r{/(.*)}.source)
 
diff --git a/Library/Homebrew/test/testing_env.rb b/Library/Homebrew/test/testing_env.rb
index 269fc7445d..64f1ccfd38 100644
--- a/Library/Homebrew/test/testing_env.rb
+++ b/Library/Homebrew/test/testing_env.rb
@@ -27,7 +27,7 @@ HOMEBREW_WWW           = 'http://example.com'
 HOMEBREW_CURL_ARGS     = '-fsLA'
 HOMEBREW_VERSION       = '0.9-test'
 
-HOMEBREW_TAP_FORMULA_REGEX = %r{^([\w_-]+)/([\w_-]+)/([\w_-]+)$}
+HOMEBREW_TAP_FORMULA_REGEX = %r{^([\w-]+)/([\w-]+)/([\w-]+)$}
 
 RUBY_BIN = Pathname.new(RbConfig::CONFIG['bindir'])
 RUBY_PATH = RUBY_BIN + RbConfig::CONFIG['ruby_install_name'] + RbConfig::CONFIG['EXEEXT']