diff --git a/src/Language/Haskell/Brittany/Internal/Config/Types.hs b/src/Language/Haskell/Brittany/Internal/Config/Types.hs
index 80a8018..96b4863 100644
--- a/src/Language/Haskell/Brittany/Internal/Config/Types.hs
+++ b/src/Language/Haskell/Brittany/Internal/Config/Types.hs
@@ -21,7 +21,6 @@ import Data.Data ( Data )
 import Data.Coerce ( Coercible, coerce )
 
 import Data.Semigroup.Generic
-
 import Data.Semigroup ( Last, Option )
 
 import Data.CZipWith
@@ -154,6 +153,25 @@ instance Semigroup.Semigroup (CPreProcessorConfig Option) where
 instance Semigroup.Semigroup (CConfig Option) where
   (<>) = gmappend
 
+instance Monoid (CDebugConfig Option) where
+  mempty = gmempty
+  mappend = gmappend
+instance Monoid (CLayoutConfig Option) where
+  mempty = gmempty
+  mappend = gmappend
+instance Monoid (CErrorHandlingConfig Option) where
+  mempty = gmempty
+  mappend = gmappend
+instance Monoid (CForwardOptions Option) where
+  mempty = gmempty
+  mappend = gmappend
+instance Monoid (CPreProcessorConfig Option) where
+  mempty = gmempty
+  mappend = gmappend
+instance Monoid (CConfig Option) where
+  mempty = gmempty
+  mappend = gmappend
+
 aesonDecodeOptionsBrittany :: Aeson.Options
 aesonDecodeOptionsBrittany = Aeson.defaultOptions
   { Aeson.omitNothingFields = True