1 files changed, 7 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_fail/T18455.hs b/testsuite/tests/typecheck/should_fail/T18455.hs
new file mode 100644
index 0000000000..ad151ae9a7
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T18455.hs
@@ -0,0 +1,7 @@
+{-# LANGUAGE RankNTypes #-}
+module T18455 where
+
+class C a
+
+instance C (Either a b) where
+  {-# SPECIALISE instance forall a. forall b. C (Either a b) #-}