diff --git a/lib/mongo/connection.rb b/lib/mongo/connection.rb
index 30ccbec..013ed29 100644
--- a/lib/mongo/connection.rb
+++ b/lib/mongo/connection.rb
@@ -32,7 +32,7 @@ module Mongo
     STANDARD_HEADER_SIZE = 16
     RESPONSE_HEADER_SIZE = 20
 
-    MONGODB_URI_MATCHER = /(([.\w\d]+):([\w\d]+)@)?([-.\w\d]+)(:([\w\d]+))?(\/([-\d\w]+))?/
+    MONGODB_URI_MATCHER = /(([-_.\w\d]+):([-_\w\d]+)@)?([-.\w\d]+)(:([\w\d]+))?(\/([-\d\w]+))?/
     MONGODB_URI_SPEC = "mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/database]"
 
     attr_reader :logger, :size, :host, :port, :nodes, :auths, :sockets, :checked_out
diff --git a/test/unit/connection_test.rb b/test/unit/connection_test.rb
index fbd1534..199b73e 100644
--- a/test/unit/connection_test.rb
+++ b/test/unit/connection_test.rb
@@ -88,6 +88,13 @@ class ConnectionTest < Test::Unit::TestCase
         assert_equal auth_hash, @conn.auths[1]
       end
 
+      should "parse a uri with a hyphen & underscore in the username or password" do
+        @conn = Connection.from_uri("mongodb://hyphen-user_name:p-s_s@localhost:27017/db", :connect => false)
+        assert_equal ['localhost', 27017], @conn.nodes[0]
+        auth_hash = { 'db_name' => 'db', 'username' => 'hyphen-user_name', "password" => 'p-s_s' }
+        assert_equal auth_hash, @conn.auths[0]
+      end
+
       should "attempt to connect" do
         TCPSocket.stubs(:new).returns(new_mock_socket)
         @conn = Connection.from_uri("mongodb://localhost", :connect => false)