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diff --git a/testsuite/tests/typecheck/should_run/tcrun039.hs b/testsuite/tests/typecheck/should_run/tcrun039.hs
new file mode 100644
index 0000000000..916d5330e4
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+++ b/testsuite/tests/typecheck/should_run/tcrun039.hs
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+{-# LANGUAGE GADTs, ExplicitForAll #-}
+
+-- Test for GADTs and implication constraints
+
+module Main where
+
+data T a where
+  MkT :: Num a => a -> T a
+
+f :: Read a => T a -> String -> a
+f (MkT n) s = n + read s
+
+----------------
+data GADT a where
+  MkG :: Num a => a -> GADT [a]
+
+g :: forall b. Read b => GADT b -> String -> b
+g (MkG n) s = -- Here we know Read [b]
+	      n : (read s)
+
+main = do print (f (MkT (3::Int)) "4")
+          print (g (MkG (3::Int)) "[4,5]")