diff --git a/test/test.hs b/test/test.hs
index 38238b5..c3a99b0 100644
--- a/test/test.hs
+++ b/test/test.hs
@@ -35,3 +35,3 @@ testPattern = 0xdeadbeef
 
-type PolyTest = (AtomicBits a, Storable a, Integral a, Bounded a, Show a) => a -> Assertion
+type PolyTest = forall a . (AtomicBits a, Storable a, Integral a, Bounded a, Show a) => a -> Assertion