diff --git a/src/Database/Esqueleto/Experimental/Aggregates.hs b/src/Database/Esqueleto/Experimental/Aggregates.hs
index b3759b3..9ab8f96 100644
--- a/src/Database/Esqueleto/Experimental/Aggregates.hs
+++ b/src/Database/Esqueleto/Experimental/Aggregates.hs
@@ -55,6 +55,12 @@ type instance MaybeValueTyToMaybeEntityTy (Aggregate (Value (Maybe val))) ent =
 type instance UnMaybeTy (Aggregate (Value (Maybe val))) = Aggregate (Value val)
 type instance UnMaybeTy (Aggregate (Maybe (Entity ent))) = Aggregate (Entity ent)
 
+test :: (PersistEntity ent, PersistField a, Integral n)
+     => SqlExpr (Maybe (Entity ent))
+     -> EntityField ent a
+     -> SqlExpr (Value b)
+     -> SqlExpr (Value c)
+     -> SqlQuery (SqlExpr (Value (Maybe a)), SqlExpr (Value b), SqlExpr (Value n), SqlExpr (Value Int))
 test ent field y other = do
     groupBy (ent, y) $ \(ent', y') ->
         pure (ent' ?. field, y', sum_ other, countRows_)
diff --git a/test/Common/Test.hs b/test/Common/Test.hs
index 8eb157b..2c07d02 100644
--- a/test/Common/Test.hs
+++ b/test/Common/Test.hs
@@ -454,10 +454,10 @@ testSubSelect run = do
             eres <- try $ run $ do
                 setup
                 bad <- select $
-                    from $ \n -> do
+                    from $ \(n :: SqlExpr (Entity Numbers)) -> do
                     pure $ (,) (n ^. NumbersInt) $
                         subSelectUnsafe $
-                        from $ \n' -> do
+                        from $ \(n' :: SqlExpr (Entity Numbers)) -> do
                         pure (just (n' ^. NumbersDouble))
                 good <- select $
                     from $ \n -> do
@@ -480,10 +480,10 @@ testSubSelect run = do
             eres <- try $ run $ do
                 setup
                 select $
-                    from $ \n -> do
+                    from $ \(n :: SqlExpr (Entity Numbers)) -> do
                     pure $ (,) (n ^. NumbersInt) $
                         subSelectUnsafe $
-                        from $ \n' -> do
+                        from $ \(n' :: SqlExpr (Entity Numbers)) -> do
                         where_ $ val False
                         pure (n' ^. NumbersDouble)
             case eres of