diff --git a/testsuite/tests/th/T4135.hs b/testsuite/tests/th/T4135.hs
new file mode 100644
index 0000000000000000000000000000000000000000..03ff2fe1f9ec242cd9781d5aea3d5e12acd9574b
--- /dev/null
+++ b/testsuite/tests/th/T4135.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE TypeFamilies,TemplateHaskell #-}
+module Bug where
+
+import Language.Haskell.TH
+import System.IO
+
+class C a where
+    type T a
+
+$(do { ds <- [d|  
+           	 instance C (Maybe a) where
+           	    type T (Maybe a) = Char
+             |]
+     ; runIO $ do { putStrLn (pprint ds); hFlush stdout }
+     ; return ds })
+
diff --git a/testsuite/tests/th/T4135.stdout b/testsuite/tests/th/T4135.stdout
new file mode 100644
index 0000000000000000000000000000000000000000..0519ecba6ea913e21689ec692e81e9e4973fbf73
--- /dev/null
+++ b/testsuite/tests/th/T4135.stdout
@@ -0,0 +1 @@
+ 
\ No newline at end of file
diff --git a/testsuite/tests/th/all.T b/testsuite/tests/th/all.T
index 6fb56a8fa72751852847550f984dcec8824efe30..e692d28cf9d21e4fa2cdcce47ea42983d23b7f6a 100644
--- a/testsuite/tests/th/all.T
+++ b/testsuite/tests/th/all.T
@@ -225,4 +225,5 @@ test('T5883', normal, compile, ['-v0 -dsuppress-uniques -ddump-splices'])
 test('T5882', normal, compile, ['-v0'])
 test('T5886', extra_clean(['T5886a.hi','T5886a.o']), 
               multimod_compile, ['T5886','-v0'])
+test('T4135', normal, compile, ['-v0'])