diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 [![Travis CI Status](https://travis-ci.org/jfischoff/tmp-postgres.svg?branch=master)](http://travis-ci.org/jfischoff/tmp-postgres)
 # tmp-postgres
 
-`tmp-postgres` provides functions creating a temporary @postgres@ instance.
+`tmp-postgres` provides functions creating a temporary `postgres` instance.
 By default it will create a temporary directory for the data,
 a random port for listening and a temporary directory for a UNIX
 domain socket.
diff --git a/src/Database/Postgres/Temp/Internal.hs b/src/Database/Postgres/Temp/Internal.hs
--- a/src/Database/Postgres/Temp/Internal.hs
+++ b/src/Database/Postgres/Temp/Internal.hs
@@ -14,6 +14,7 @@
 import Control.Monad.Trans.Cont
 import Control.Monad.Trans.Class
 import qualified Database.PostgreSQL.Simple as PG
+import qualified Data.Map.Strict as Map
 
 -- | Handle for holding temporary resources, the @postgres@ process handle
 --   and postgres connection information. The 'DB' also includes the
@@ -64,15 +65,15 @@
   { configPlan = mempty
     { partialPlanLogger = pure mempty
     , partialPlanConfig = Mappend defaultPostgresConfig
-    , partialPlanCreateDb = Mappend $ pure mempty
-        { partialProcessConfigCmdLine = Mappend ["test"]
-        }
+    , partialPlanCreateDb = Mappend Nothing
     , partialPlanInitDb = Mappend $ pure mempty
-      { partialProcessConfigCmdLine = Mappend ["--no-sync"]
+      { partialProcessConfigCmdLine = Mappend $ mempty
+          { partialCommandLineArgsKeyBased = Map.singleton "--no-sync" Nothing
+          }
       }
     , partialPlanPostgres = mempty
         { partialPostgresPlanClientConfig = mempty
-          { Client.dbname = pure "test"
+          { Client.dbname = pure "postgres"
           }
         }
     }
@@ -181,16 +182,6 @@
 --   want to create a database owned by a specific user you will also log in as
 --   among other use cases. It is possible some 'Client.Options' are not
 --   supported so don't hesitate to open an issue on github if you find one.
---   This function works around a difficulty with appending options to
---   the 'createdb' plan by mappending to 'defaultConfig' and
---   optionally replacing the database name.
 optionsToDefaultConfig :: Client.Options -> Config
 optionsToDefaultConfig opts@Client.Options {..} =
-  let thePartialPlan = configPlan defaultConfig
-      noDbDefault    = defaultConfig
-        { configPlan = thePartialPlan
-            { partialPlanCreateDb = mempty
-            }
-        }
-      generateConfig = optionsToConfig opts
-  in noDbDefault <> generateConfig
+  defaultConfig <> optionsToConfig opts
diff --git a/src/Database/Postgres/Temp/Internal/Partial.hs b/src/Database/Postgres/Temp/Internal/Partial.hs
--- a/src/Database/Postgres/Temp/Internal/Partial.hs
+++ b/src/Database/Postgres/Temp/Internal/Partial.hs
@@ -31,6 +31,8 @@
 import Control.Monad.Trans.Cont
 import Control.Monad.Trans.Class
 import System.IO.Error
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as Map
 
 {- |
 'Lastoid' is helper for overriding configuration values.
@@ -66,12 +68,51 @@
   Replace a -> a
   Mappend a -> a
 
+-- | A type to help combine command line arguments.
+data PartialCommandLineArgs = PartialCommandLineArgs
+  { partialCommandLineArgsKeyBased   :: Map String (Maybe String)
+  -- ^ Arguments of the form @-h foo@, @--host=foo@ and @--switch@.
+  --   The key is `mappend`ed with value so the key should include
+  --   the space or equals (as shown in the first two examples
+  --   respectively).
+  , partialCommandLineArgsIndexBased :: Map Int String
+  -- ^ Arguments that appear at the end of the key based
+  --   arguments.
+  }
+  deriving stock (Generic, Show, Eq)
+  deriving Monoid via GenericMonoid PartialCommandLineArgs
+
+instance Semigroup PartialCommandLineArgs where
+  x <> y = PartialCommandLineArgs
+    { partialCommandLineArgsKeyBased   =
+        partialCommandLineArgsKeyBased y <> partialCommandLineArgsKeyBased x
+    , partialCommandLineArgsIndexBased =
+        partialCommandLineArgsIndexBased y <> partialCommandLineArgsIndexBased x
+    }
+
+-- | Take values as long as the index is the successor of the
+--   last index.
+takeWhileInSequence :: [(Int, a)] -> [a]
+takeWhileInSequence ((0, x):xs) = x : go 0 xs where
+  go _ [] = []
+  go prev ((next, a):rest)
+    | prev + 1 == next = a : go next rest
+    | otherwise = []
+takeWhileInSequence _ = []
+
+-- | This convert the 'PartialCommandLineArgs' to '
+completeCommandLineArgs :: PartialCommandLineArgs -> [String]
+completeCommandLineArgs PartialCommandLineArgs {..}
+  =  map (\(name, mvalue) -> maybe name (name <>) mvalue)
+       (Map.toList partialCommandLineArgsKeyBased)
+  <> takeWhileInSequence (Map.toList partialCommandLineArgsIndexBased)
+
 -- | The monoidial version of 'ProcessConfig'. Used to combine overrides with
 --   defaults when creating a 'ProcessConfig'.
 data PartialProcessConfig = PartialProcessConfig
-  { partialProcessConfigEnvVars :: Lastoid [(String, String)]
+  { partialProcessConfigEnvVars :: Lastoid (Map String String)
   -- ^ A monoid for combine environment variables or replacing them
-  , partialProcessConfigCmdLine :: Lastoid [String]
+  , partialProcessConfigCmdLine :: Lastoid PartialCommandLineArgs
   -- ^ A monoid for combine command line arguments or replacing them
   , partialProcessConfigStdIn   :: Last Handle
   -- ^ A monoid for configuring the standard input 'Handle'
@@ -81,9 +122,23 @@
   -- ^ A monoid for configuring the standard error 'Handle'
   }
   deriving stock (Generic)
-  deriving Semigroup via GenericSemigroup PartialProcessConfig
   deriving Monoid    via GenericMonoid PartialProcessConfig
 
+instance Semigroup PartialProcessConfig where
+  x <> y = PartialProcessConfig
+    { partialProcessConfigEnvVars = fmap getDual $
+        fmap Dual (partialProcessConfigEnvVars x) <>
+          fmap Dual (partialProcessConfigEnvVars y)
+    , partialProcessConfigCmdLine =
+        partialProcessConfigCmdLine x <> partialProcessConfigCmdLine y
+    , partialProcessConfigStdIn   =
+        partialProcessConfigStdIn x <> partialProcessConfigStdIn y
+    , partialProcessConfigStdOut  =
+        partialProcessConfigStdOut x <> partialProcessConfigStdOut y
+    , partialProcessConfigStdErr  =
+        partialProcessConfigStdErr x <> partialProcessConfigStdErr y
+    }
+
 -- | The 'standardProcessConfig' sets the handles to 'stdin', 'stdout' and
 --   'stderr' and inherits the environment variables from the calling
 --   process.
@@ -91,7 +146,7 @@
 standardProcessConfig = do
   env <- getEnvironment
   pure mempty
-    { partialProcessConfigEnvVars = Replace env
+    { partialProcessConfigEnvVars = Replace $ Map.fromList env
     , partialProcessConfigStdIn   = pure stdin
     , partialProcessConfigStdOut  = pure stdout
     , partialProcessConfigStdErr  = pure stderr
@@ -112,8 +167,9 @@
 completeProcessConfig
   :: PartialProcessConfig -> Either [String] ProcessConfig
 completeProcessConfig PartialProcessConfig {..} = validationToEither $ do
-  let processConfigEnvVars = getLastoid partialProcessConfigEnvVars
-      processConfigCmdLine = getLastoid partialProcessConfigCmdLine
+  let processConfigEnvVars = Map.toList $ getLastoid partialProcessConfigEnvVars
+      processConfigCmdLine = completeCommandLineArgs $
+        getLastoid partialProcessConfigCmdLine
   processConfigStdIn  <-
     getOption "partialProcessConfigStdIn" partialProcessConfigStdIn
   processConfigStdOut <-
@@ -197,8 +253,8 @@
 
 -- | Many processes require a \"host\" flag. We can generate one from the
 --   'SocketClass'.
-socketClassToHostFlag :: SocketClass -> [String]
-socketClassToHostFlag x = ["-h", socketClassToHost x]
+socketClassToHostFlag :: SocketClass -> [(String, Maybe String)]
+socketClassToHostFlag x = [("-h", Just (socketClassToHost x))]
 
 -- | Get the IP address, host name or UNIX domain socket directory
 --   as a 'String'
@@ -343,10 +399,12 @@
   , partialPlanDataDirectory = pure dataDirectory
   , partialPlanPostgres = mempty
       { partialPostgresPlanProcessConfig = mempty
-          { partialProcessConfigCmdLine = Mappend
-              [ "-p", show port
-              , "-D", dataDirectory
-              ]
+          { partialProcessConfigCmdLine = Mappend $ mempty
+              { partialCommandLineArgsKeyBased = Map.fromList
+                  [ ("-p", Just $ show port)
+                  , ("-D", Just dataDirectory)
+                  ]
+              }
           }
       , partialPostgresPlanClientConfig = mempty
           { Client.host = pure $ socketClassToHost socketClass
@@ -354,13 +412,18 @@
           }
       }
   , partialPlanCreateDb = Mappend $ Just $ mempty
-      { partialProcessConfigCmdLine = Mappend $
-          socketClassToHostFlag socketClass <>
-          ["-p", show port]
+      { partialProcessConfigCmdLine = Mappend $ mempty
+          { partialCommandLineArgsKeyBased = Map.fromList $
+              socketClassToHostFlag socketClass <>
+              [("-p ", Just $ show port)]
+          }
       }
   , partialPlanInitDb = Mappend $ Just $ mempty
-      { partialProcessConfigCmdLine = Mappend $
-          ["--pgdata=" <> dataDirectory]
+      { partialProcessConfigCmdLine = Mappend $ mempty
+          { partialCommandLineArgsKeyBased = Map.fromList $
+              [("--pgdata=", Just dataDirectory)]
+          }
+
       }
   }
 
@@ -422,10 +485,14 @@
   Nothing -> mempty
   Just user -> mempty
     { partialPlanCreateDb = Mappend $ Just $ mempty
-      { partialProcessConfigCmdLine = Mappend ["--username=" <> user]
+      { partialProcessConfigCmdLine = Mappend $ mempty
+          { partialCommandLineArgsKeyBased = Map.singleton "--username=" $ Just user
+          }
       }
     , partialPlanInitDb = Mappend $ Just $ mempty
-      { partialProcessConfigCmdLine = Mappend ["--username=" <> user]
+      { partialProcessConfigCmdLine =  Mappend $ mempty
+          { partialCommandLineArgsKeyBased = Map.singleton "--username=" $ Just user
+          }
       }
     }
 
@@ -434,7 +501,9 @@
   Nothing -> mempty
   Just dbName -> mempty
     { partialPlanCreateDb = Mappend $ Just $ mempty
-      { partialProcessConfigCmdLine = Mappend [dbName]
+      { partialProcessConfigCmdLine = Mappend $ mempty
+        { partialCommandLineArgsIndexBased = Map.singleton 0 dbName
+        }
       }
     }
 
diff --git a/test/Spec.hs b/test/Spec.hs
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -19,6 +19,7 @@
 import Control.Concurrent
 import Data.Monoid
 import Network.Socket.Free (getFreePort)
+import qualified Data.Map.Strict as Map
 
 main :: IO ()
 main = hspec spec
@@ -49,7 +50,7 @@
     let Resources {..} = dbResources
         Plan {..} = resourcesPlan
         PostgresPlan {..} = planPostgres
-    Client.dbname postgresPlanClientConfig `shouldBe` pure "test"
+    Client.dbname postgresPlanClientConfig `shouldBe` pure "postgres"
     let Temporary tmpDataDir = resourcesDataDir
     tmpDataDir `shouldStartWith` "/tmp/tmp-postgres-data"
     let Just port = getLast $ Client.port postgresPlanClientConfig
@@ -84,12 +85,12 @@
                       }
                   }
               , partialPlanInitDb = Mappend $ pure $ mempty
-                  { partialProcessConfigCmdLine = Mappend
-                      ["--user", "user-name"
-                      ]
-                  , partialProcessConfigEnvVars = Mappend
-                      [ ("PGPASSWORD", "password")
-                      ]
+                  { partialProcessConfigCmdLine = Mappend $ mempty
+                      { partialCommandLineArgsKeyBased =
+                          Map.singleton "--username=" $ Just "user-name"
+                      }
+                  , partialProcessConfigEnvVars = Mappend $
+                      Map.singleton "PGPASSWORD" "password"
                   }
               , partialPlanConfig = Mappend [extraConfig]
               }
@@ -97,14 +98,15 @@
     -- hmm maybe I should provide lenses
     let combinedResources = defaultConfig <> customPlan
         finalCombinedResources = updateCreateDb combinedResources $ Mappend $ pure $ initialCreateDbConfig
-          { partialProcessConfigCmdLine = Mappend
-              ["--user", "user-name"
-              , expectedDbName
-              ]
-          , partialProcessConfigEnvVars = Mappend
-              [ ("PGPASSWORD", "password")
-              ]
+          { partialProcessConfigCmdLine = Mappend $ mempty
+          { partialCommandLineArgsKeyBased =
+              Map.singleton "--username=" $ Just "user-name"
+          , partialCommandLineArgsIndexBased =
+              Map.singleton 0 expectedDbName
           }
+          , partialProcessConfigEnvVars = Mappend $
+              Map.singleton "PGPASSWORD" "password"
+          }
 
     action finalCombinedResources $ \db@DB {..} -> do
       bracket (PG.connectPostgreSQL $ toConnectionString db) PG.close $ \conn -> do
@@ -246,19 +248,19 @@
             =<< either throwIO pure
             =<< start) stop f
     before (pure $ Runner startAction) $ do
-      someStandardTests "test"
+      someStandardTests "postgres"
       defaultConfigShouldMatchDefaultPlan
 
   describe "withRestart" $ do
     let startAction f = bracket (either throwIO pure =<< start) stop $ \db ->
           either throwIO pure =<< withRestart db f
     before (pure $ Runner startAction) $ do
-      someStandardTests "test"
+      someStandardTests "postgres"
       defaultConfigShouldMatchDefaultPlan
 
   describe "start/stop" $ do
     before (pure $ Runner $ \f -> bracket (either throwIO pure =<< start) stop f) $ do
-      someStandardTests "test"
+      someStandardTests "postgres"
       defaultConfigShouldMatchDefaultPlan
       it "stopPostgres cannot be connected to" $ withRunner $ \db -> do
         stopPostgres db `shouldReturn` ExitSuccess
@@ -279,7 +281,10 @@
 
     let invalidCreateDbPlan = updateCreateDb defaultConfig $
           Mappend $ pure $ theStandardProcessConfig
-            { partialProcessConfigCmdLine = Mappend ["template1"]
+            { partialProcessConfigCmdLine = Mappend $ mempty
+              { partialCommandLineArgsIndexBased =
+                  Map.singleton 0 "template1"
+              }
             }
     before (pure $ Runner $ \f -> bracket (either throwIO pure =<< startWith invalidCreateDbPlan) stop f) $
       createDbThrowsIfTheDbExists
@@ -299,10 +304,10 @@
       someStandardTests "template1"
 
     before (pure $ Runner $ \f -> bracket (either throwIO pure =<< startWith defaultIpPlan) stop f) $
-      someStandardTests "test"
+      someStandardTests "postgres"
 
     before (pure $ Runner $ \f -> bracket (either throwIO pure =<< startWith specificHostIpPlan) stop f) $
-      someStandardTests "test"
+      someStandardTests "postgres"
 
     thePort <- runIO getFreePort
     let planFromCustomUserDbConnection = optionsToDefaultConfig mempty
diff --git a/tmp-postgres.cabal b/tmp-postgres.cabal
--- a/tmp-postgres.cabal
+++ b/tmp-postgres.cabal
@@ -1,5 +1,5 @@
 name:                tmp-postgres
-version:             1.0.1.0
+version:             1.2.0.0
 synopsis: Start and stop a temporary postgres
 description:
  @tmp-postgres@ provides functions creating a temporary @postgres@ instance.
@@ -64,6 +64,7 @@
                , generic-monoid
                , either
                , transformers
+               , containers
   ghc-options: -Wall
   default-language:    Haskell2010
 
@@ -73,6 +74,7 @@
   hs-source-dirs:      test
   main-is:             Spec.hs
   build-depends:       base
+                     , containers
                      , postgresql-libpq
                      , tmp-postgres
                      , hspec
@@ -88,6 +90,7 @@
                      , transformers
                      , postgres-options
                      , port-utils
+
   ghc-options:        -Wall -threaded -rtsopts -with-rtsopts=-N
   default-language:    Haskell2010
   default-extensions: LambdaCase