diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index dd6870e0d..49c3b3aa2 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -251,6 +251,12 @@ jobs:
       - name: tests
         run: |
           $CABAL v2-test $ARG_COMPILER $ARG_TESTS $ARG_BENCH all --test-show-details=direct
+          $CABAL v2-test $ARG_COMPILER $ARG_TESTS $ARG_BENCH all --test-show-details=direct --test-options="--pattern=intset --quickcheck-tests=10000"
+          $CABAL v2-test $ARG_COMPILER $ARG_TESTS $ARG_BENCH all --test-show-details=direct --test-options="--pattern=intset --quickcheck-tests=1000   --quickcheck-max-size=100"
+          $CABAL v2-test $ARG_COMPILER $ARG_TESTS $ARG_BENCH all --test-show-details=direct --test-options="--pattern=intset --quickcheck-tests=10     --quickcheck-max-size=1000"
+          $CABAL v2-test $ARG_COMPILER $ARG_TESTS $ARG_BENCH all --test-show-details=direct --test-options="--pattern=intmap --quickcheck-tests=10000"
+          $CABAL v2-test $ARG_COMPILER $ARG_TESTS $ARG_BENCH all --test-show-details=direct --test-options="--pattern=intmap --quickcheck-tests=1000   --quickcheck-max-size=100"
+          $CABAL v2-test $ARG_COMPILER $ARG_TESTS $ARG_BENCH all --test-show-details=direct --test-options="--pattern=intmap --quickcheck-tests=10     --quickcheck-max-size=1000"
       - name: haddock
         run: |
           if [ $((HCNUMVER >= 80200)) -ne 0 ] ; then $CABAL v2-haddock --haddock-all $ARG_COMPILER --with-haddock $HADDOCK $ARG_TESTS $ARG_BENCH all ; fi
diff --git a/containers-tests/tests/intmap-properties.hs b/containers-tests/tests/intmap-properties.hs
index 8d26439c0..e912fd4b9 100644
--- a/containers-tests/tests/intmap-properties.hs
+++ b/containers-tests/tests/intmap-properties.hs
@@ -219,16 +219,16 @@ apply3 f a b c = apply f (a, b, c)
 
 
 {--------------------------------------------------------------------
-  Arbitrary, reasonably balanced trees
+  Arbitrary IntMaps, including those with large keys
 --------------------------------------------------------------------}
 
 instance Arbitrary a => Arbitrary (IntMap a) where
-  arbitrary = fmap fromList arbitrary
+  arbitrary = fmap (fromList . fmap (\(k,v) -> (getLarge k, v))) arbitrary
 
 newtype NonEmptyIntMap a = NonEmptyIntMap {getNonEmptyIntMap :: IntMap a} deriving (Eq, Show)
 
 instance Arbitrary a => Arbitrary (NonEmptyIntMap a) where
-  arbitrary = fmap (NonEmptyIntMap . fromList . getNonEmpty) arbitrary
+  arbitrary = fmap (NonEmptyIntMap . fromList  . fmap (\(k,v) -> (getLarge k, v)) . getNonEmpty) arbitrary
 
 
 ------------------------------------------------------------------------
diff --git a/containers-tests/tests/intset-properties.hs b/containers-tests/tests/intset-properties.hs
index d0c10bf0b..8b769e71d 100644
--- a/containers-tests/tests/intset-properties.hs
+++ b/containers-tests/tests/intset-properties.hs
@@ -109,11 +109,11 @@ test_split = do
    split 3 (fromList [1..5]) @?= (fromList [1,2], fromList [4,5])
 
 {--------------------------------------------------------------------
-  Arbitrary, reasonably balanced trees
+  Arbitrary IntSets, including those with large elements
 --------------------------------------------------------------------}
 instance Arbitrary IntSet where
   arbitrary = do{ xs <- arbitrary
-                ; return (fromList xs)
+                ; return (fromList (fmap getLarge xs))
                 }
 
 {--------------------------------------------------------------------