diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 # Change Log
 All notable changes to this project will be documented in this file.
 This project adheres to [Package Versioning Policy](https://wiki.haskell.org/Package_versioning_policy).
+## [2.6.0.1] - 2020-02-01
+
+## Fixed
+- Parsing hostname with underscores in readHostPortM.
 
 ## [2.6.0.0] - 2020-01-03
 
diff --git a/Database/MongoDB/Connection.hs b/Database/MongoDB/Connection.hs
--- a/Database/MongoDB/Connection.hs
+++ b/Database/MongoDB/Connection.hs
@@ -86,7 +86,7 @@
 -- ^ Read string \"hostname:port\" as @Host hosthame (PortNumber port)@ or \"hostname\" as @host hostname@ (default port). Fail if string does not match either syntax.
 -- TODO: handle Service port
 readHostPortM = either (fail . show) return . parse parser "readHostPort" where
-    hostname = many1 (letter <|> digit <|> char '-' <|> char '.')
+    hostname = many1 (letter <|> digit <|> char '-' <|> char '.' <|> char '_')
     parser = do
         spaces
         h <- hostname
diff --git a/mongoDB.cabal b/mongoDB.cabal
--- a/mongoDB.cabal
+++ b/mongoDB.cabal
@@ -1,5 +1,5 @@
 Name:           mongoDB
-Version:        2.6.0.0
+Version:        2.6.0.1
 Synopsis:       Driver (client) for MongoDB, a free, scalable, fast, document
                 DBMS
 Description:    This package lets you connect to MongoDB servers and