diff --git a/Annex/Debug.hs b/Annex/Debug.hs
index e2f04b4f9a..f3626ffaa1 100644
--- a/Annex/Debug.hs
+++ b/Annex/Debug.hs
@@ -1,6 +1,6 @@
 {- git-annex debugging
  -
- - Copyright 2021-2023 Joey Hess <id@joeyh.name>
+ - Copyright 2021 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -8,11 +8,8 @@
 module Annex.Debug (
 	DebugSelector(..),
 	DebugSource(..),
-	RawDebugMessage(..),
 	debug,
-	debug',
 	fastDebug,
-	fastDebug',
 	configureDebug,
 	debugSelectorFromGitConfig,
 	parseDebugSelector,
@@ -20,7 +17,7 @@ module Annex.Debug (
 
 import Common
 import qualified Annex
-import Utility.Debug hiding (fastDebug, fastDebug')
+import Utility.Debug hiding (fastDebug)
 import qualified Utility.Debug
 import Annex.Debug.Utility
 
@@ -28,11 +25,7 @@ import Annex.Debug.Utility
 -- is read from the Annex monad, which avoids any IORef access overhead
 -- when debugging is not enabled.
 fastDebug :: DebugSource -> String -> Annex.Annex ()
-fastDebug = fastDebug'
-
-fastDebug' :: DebugMessage msg => DebugSource -> msg -> Annex.Annex ()
-fastDebug' src msg = do
+fastDebug src msg = do
 	rd <- Annex.getRead id
 	when (Annex.debugenabled rd) $
-		liftIO $ Utility.Debug.fastDebug' (Annex.debugselector rd) src msg
-	
+		liftIO $ Utility.Debug.fastDebug (Annex.debugselector rd) src msg
diff --git a/Messages.hs b/Messages.hs
index 5a318a2c68..7d865b29d6 100644
--- a/Messages.hs
+++ b/Messages.hs
@@ -50,7 +50,6 @@ module Messages (
 	outputMessage,
 	withMessageState,
 	MessageState,
-	explain,
 	prompt,
 	mkPrompter,
 	sanitizeTopLevelExceptionMessages,
@@ -282,11 +281,6 @@ debugDisplayer = do
 		S.hPutStr stderr (safeOutput s <> "\n")
 		hFlush stderr
 
-explain :: Maybe String -> String -> Annex ()
-explain Nothing _ = return ()
-explain (Just f) msg = fastDebug' "explain" $ 
-	RawDebugMessage ('[' : f ++ " " ++ msg ++ "]")
-
 {- Should commands that normally output progress messages have that
  - output disabled? -}
 commandProgressDisabled :: Annex Bool
diff --git a/Utility/Debug.hs b/Utility/Debug.hs
index b7fe471f2e..6e6e701162 100644
--- a/Utility/Debug.hs
+++ b/Utility/Debug.hs
@@ -1,6 +1,6 @@
 {- Debug output
  -
- - Copyright 2021-2023 Joey Hess <id@joeyh.name>
+ - Copyright 2021 Joey Hess <id@joeyh.name>
  -
  - License: BSD-2-clause
  -}
@@ -12,14 +12,10 @@
 module Utility.Debug (
 	DebugSource(..),
 	DebugSelector(..),
-	DebugMessage,
-	RawDebugMessage(..),
 	configureDebug,
 	getDebugSelector,
 	debug,
-	debug',
-	fastDebug,
-	fastDebug'
+	fastDebug
 ) where
 
 import qualified Data.ByteString as S
@@ -54,22 +50,6 @@ instance Sem.Semigroup DebugSelector where
 instance Monoid DebugSelector where
 	mempty = NoDebugSelector
 
-class DebugMessage msg where
-	formatDebugMessage :: DebugSource -> msg -> IO S.ByteString
-
-instance DebugMessage String where
-	formatDebugMessage (DebugSource src) msg = do
-		t <- encodeBS . formatTime defaultTimeLocale "[%F %X%Q]"
-			<$> getZonedTime
-		return (t <> " (" <> src <> ") " <> encodeBS msg)
-
--- Debug message to be displayed without the usual time stamp 
--- and source information.
-newtype RawDebugMessage = RawDebugMessage String
-
-instance DebugMessage RawDebugMessage where
-	formatDebugMessage _ (RawDebugMessage msg) = pure (encodeBS msg)
-
 -- | Configures debugging.
 configureDebug
 	:: (S.ByteString -> IO ())
@@ -96,10 +76,7 @@ debugConfigGlobal = unsafePerformIO $ newIORef (dontshow, selectnone)
 -- have to consult a IORef each time, using it in a tight loop may slow
 -- down the program.
 debug :: DebugSource -> String -> IO ()
-debug = debug'
-
-debug' :: DebugMessage msg => DebugSource -> msg -> IO ()
-debug' src msg = readIORef debugConfigGlobal >>= \case
+debug src msg = readIORef debugConfigGlobal >>= \case
 	(displayer, NoDebugSelector) ->
 		displayer =<< formatDebugMessage src msg
 	(displayer, DebugSelector p)
@@ -111,12 +88,15 @@ debug' src msg = readIORef debugConfigGlobal >>= \case
 -- When the DebugSelector does not let the message be displayed, this runs
 -- very quickly, allowing it to be used inside tight loops.
 fastDebug :: DebugSelector -> DebugSource -> String -> IO ()
-fastDebug = fastDebug'
-
-fastDebug' :: DebugMessage msg => DebugSelector -> DebugSource -> msg -> IO ()
-fastDebug' NoDebugSelector src msg = do
+fastDebug NoDebugSelector src msg = do
 	(displayer, _) <- readIORef debugConfigGlobal
 	displayer =<< formatDebugMessage src msg
-fastDebug' (DebugSelector p) src msg
-	| p src = fastDebug' NoDebugSelector src msg
+fastDebug (DebugSelector p) src msg
+	| p src = fastDebug NoDebugSelector src msg
 	| otherwise = return ()
+
+formatDebugMessage :: DebugSource -> String -> IO S.ByteString
+formatDebugMessage (DebugSource src) msg = do
+	t <- encodeBS . formatTime defaultTimeLocale "[%F %X%Q]"
+		<$> getZonedTime
+	return (t <> " (" <> src <> ") " <> encodeBS msg)