diff --git a/packages/backend-glr/happy-backend-glr.cabal b/packages/backend-glr/happy-backend-glr.cabal
index 7d8552cb..295c49dd 100644
--- a/packages/backend-glr/happy-backend-glr.cabal
+++ b/packages/backend-glr/happy-backend-glr.cabal
@@ -57,5 +57,5 @@ library
 
   default-language:    Haskell98
   default-extensions:  CPP, MagicHash, FlexibleContexts
-  ghc-options:         -Wall
+  ghc-options:         -Wall -Wincomplete-uni-patterns
   other-modules:       Paths_happy_backend_glr
diff --git a/packages/backend-lalr/happy-backend-lalr.cabal b/packages/backend-lalr/happy-backend-lalr.cabal
index 7665a43b..1e259308 100644
--- a/packages/backend-lalr/happy-backend-lalr.cabal
+++ b/packages/backend-lalr/happy-backend-lalr.cabal
@@ -56,5 +56,5 @@ library
 
   default-language:    Haskell98
   default-extensions:  CPP, MagicHash, FlexibleContexts
-  ghc-options:         -Wall
+  ghc-options:         -Wall -Wincomplete-uni-patterns
   other-modules:       Paths_happy_backend_lalr
diff --git a/packages/frontend/happy-frontend.cabal b/packages/frontend/happy-frontend.cabal
index 6c5c09f7..e264cbbb 100644
--- a/packages/frontend/happy-frontend.cabal
+++ b/packages/frontend/happy-frontend.cabal
@@ -56,7 +56,7 @@ library
 
   default-language:    Haskell98
   default-extensions:  CPP, MagicHash, FlexibleContexts
-  ghc-options: -Wall
+  ghc-options: -Wall -Wincomplete-uni-patterns -Wno-incomplete-uni-patterns
   other-modules:
         Happy.Frontend.ParseMonad
         Happy.Frontend.ParseMonad.Class