diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 Changelog for tmp-postgres
 
+1.19.0.1
+  #146 Better version hashing for making cache directories
+  Documentation fixes
+
 1.19.0.0
   #154 Change 'createDefaultCacheConfig` to `defaultCacheConfig`
 
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
@@ -450,11 +450,11 @@
   -- 'Temporary'. @\/tmp@ is a good default.
   , cacheDirectoryType      :: DirectoryType
   -- ^ Used to specify is a 'Permanent' or 'Temporary' directory should be
-  --   used. 'createDefaultCacheConfig' uses 'Permanent' @~\/.tmp-postgres@
+  --   used. 'defaultCacheConfig' uses 'Permanent' @~\/.tmp-postgres@
   --   by default.
   , cacheUseCopyOnWrite     :: Bool
   -- ^ Some operatoring system versions support flags for @cp@ that allow
-  --   \"copy on write\" which is about 2x faster. 'createDefaultCacheConfig'
+  --   \"copy on write\" which is about 2x faster. 'defaultCacheConfig'
   --   attempts to determine if the @cp@ on the path supports copy on write
   --   and sets this to 'True' if it does.
   }
diff --git a/src/Database/Postgres/Temp/Internal/Config.hs b/src/Database/Postgres/Temp/Internal/Config.hs
--- a/src/Database/Postgres/Temp/Internal/Config.hs
+++ b/src/Database/Postgres/Temp/Internal/Config.hs
@@ -608,18 +608,20 @@
     , copyDirectoryCommandCow = useCopyOnWrite
     }
 
-getInitDbVersion :: IO String
-getInitDbVersion = readProcessWithExitCode "initdb" ["--version"] "" >>= \case
+getInitDbVersion :: String
+getInitDbVersion = unsafePerformIO $ readProcessWithExitCode "initdb" ["--version"] "" >>= \case
   (ExitSuccess, outputString, _) -> do
     let
       theLastPart = last $ words outputString
       versionPart = takeWhile (\x -> isDigit x || x == '.' || x == '-') theLastPart
-    pure $ if last versionPart == '.'
-             then init versionPart
-             else versionPart
+      humanReadable = if last versionPart == '.'
+        then init versionPart
+        else versionPart
+    pure $ humanReadable <> take 8 (makeArgumentHash outputString)
 
   (startErrorExitCode, startErrorStdOut, startErrorStdErr) ->
     throwIO InitDbFailed {..}
+{-# NOINLINE getInitDbVersion #-}
 
 makeCommandLine :: String -> CompleteProcessConfig -> String
 makeCommandLine command CompleteProcessConfig {..} =
@@ -633,11 +635,12 @@
 makeArgumentHash :: String -> String
 makeArgumentHash = BSC.unpack . Base64.encode . hash . BSC.pack
 
-makeCachePath :: FilePath -> String -> IO String
-makeCachePath cacheFolder cmdLine = do
-  version <- getInitDbVersion
-  let theHash = makeArgumentHash cmdLine
-  pure $ cacheFolder <> "/" <> version <> "/" <> theHash
+makeCachePath :: FilePath -> String -> String
+makeCachePath cacheFolder cmdLine =
+  let
+    version = getInitDbVersion
+    theHash = makeArgumentHash cmdLine
+  in cacheFolder <> "/" <> version <> "/" <> theHash
 
 splitDataDirectory :: CompleteProcessConfig -> (Maybe String, CompleteProcessConfig)
 splitDataDirectory old =
@@ -677,11 +680,10 @@
       pure
       mtheDataDirectory
 
-    let theCommandLine = makeInitDbCommandLine clearedConfig
-
-    cachePath <- makeCachePath cacheDirectory theCommandLine
-
-    let cachedDataDirectory = cachePath <> "/data"
+    let
+      theCommandLine = makeInitDbCommandLine clearedConfig
+      cachePath = makeCachePath cacheDirectory theCommandLine
+      cachedDataDirectory = cachePath <> "/data"
 
     theInitDbPlan <- doesDirectoryExist cachePath >>= \case
       True -> pure $ Nothing
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:             1.19.0.0
+version:             1.19.0.1
 synopsis: Start and stop a temporary postgres
 description: Start and stop a temporary postgres. See README.md
 homepage:            https://github.com/jfischoff/tmp-postgres#readme