diff --git a/semantic-diff.cabal b/semantic-diff.cabal
index a11fb5193..2a5bb3e42 100644
--- a/semantic-diff.cabal
+++ b/semantic-diff.cabal
@@ -116,6 +116,7 @@ library
                      , text >= 1.2.1.3
                      , these
                      , time
+                     , unix
                      , haskell-tree-sitter
                      , c
                      , go
diff --git a/src/Semantic/Log.hs b/src/Semantic/Log.hs
index 027a6e064..df3d9cae7 100644
--- a/src/Semantic/Log.hs
+++ b/src/Semantic/Log.hs
@@ -6,6 +6,8 @@ import qualified Data.Time.Format as Time
 import qualified Data.Time.LocalTime as LocalTime
 import System.Console.ANSI
 import System.IO (hIsTerminalDevice)
+import System.Posix.Process
+import System.Posix.Types
 import Text.Show
 import Text.Printf
 
@@ -30,9 +32,10 @@ data Level
 logfmtFormatter :: Options -> Message -> String
 logfmtFormatter Options{..} (Message level message pairs time) =
     showPairs
-      (  kv "time" (showTime time)
+      ( kv "time" (showTime time)
       : kv "msg" (shows message)
       : kv "level" (shows level)
+      : kv "pid" (shows optionsProcessID)
       : (uncurry kv . second shows <$> pairs) )
   . showChar '\n' $ ""
   where
@@ -66,8 +69,9 @@ data Options = Options
   { optionsEnableColour :: Bool -- ^ Whether to enable colour formatting for logging (Only works when logging to a terminal that supports ANSI colors).
   , optionsLevel :: Maybe Level -- ^ What level of messages to log. 'Nothing' disabled logging.
   , optionsPrintSource :: Bool -- ^ Whether to print the source reference when logging errors.
-  , optionsIsTerminal :: Bool -- ^ Whether a terminal is attached.
-  , optionsFormatter :: Options -> Message -> String -- ^ Log formatter to use.
+  , optionsIsTerminal :: Bool -- ^ Whether a terminal is attached (set automaticaly at runtime).
+  , optionsFormatter :: Options -> Message -> String -- ^ Log formatter to use (set automaticaly at runtime).
+  , optionsProcessID :: CPid -- ^ ProcessID (set automaticaly at runtime).
   }
 
 defaultOptions :: Options
@@ -77,14 +81,17 @@ defaultOptions = Options
   , optionsPrintSource = False
   , optionsIsTerminal = False
   , optionsFormatter = logfmtFormatter
+  , optionsProcessID = 0
   }
 
 configureOptionsForHandle :: Handle -> Options -> IO Options
 configureOptionsForHandle handle options = do
+  pid <- getProcessID
   isTerminal <- hIsTerminalDevice handle
   pure $ options
     { optionsIsTerminal = isTerminal
     , optionsFormatter = if isTerminal then terminalFormatter else logfmtFormatter
+    , optionsProcessID = pid
     }
 
 withSGRCode :: Bool -> [SGR] -> ShowS -> ShowS
diff --git a/src/SemanticCmdLine.hs b/src/SemanticCmdLine.hs
index 9aa2606fc..b7ef3e5d5 100644
--- a/src/SemanticCmdLine.hs
+++ b/src/SemanticCmdLine.hs
@@ -45,8 +45,10 @@ arguments = info (version <*> helper <*> ((,) <$> optionsParser <*> argumentsPar
       <*> options [("error", Just Log.Error), ("warning", Just Log.Warning), ("info", Just Log.Info), ("debug", Just Log.Debug), ("none", Nothing)]
             (long "log-level" <> value (Just Log.Warning) <> help "Log messages at or above this level, or disable logging entirely.")
       <*> switch (long "print-source" <> help "Include source references in logged errors where applicable.")
-      <*> pure False
-      <*> pure Log.logfmtFormatter
+      -- The rest of the logging options are set automatically at runtime.
+      <*> pure False -- IsTerminal
+      <*> pure Log.logfmtFormatter -- Formatter
+      <*> pure 0 -- ProcessID
     argumentsParser = (. Task.writeToOutput) . (>>=)
       <$> hsubparser (diffCommand <> parseCommand)
       <*> (   Right <$> strOption (long "output" <> short 'o' <> help "Output path, defaults to stdout")