diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## Version 0.9.0.3 (2024-11-25)
+
+- Fix an off-by-one error Heap.partialSort functions.
+- Support latest ghcs.
+
 ## Version 0.9.0.2 (2024-05-23)
 
 - Add `TypeOperators` pragma where needed.
diff --git a/src/Data/Vector/Algorithms/Heap.hs b/src/Data/Vector/Algorithms/Heap.hs
--- a/src/Data/Vector/Algorithms/Heap.hs
+++ b/src/Data/Vector/Algorithms/Heap.hs
@@ -188,8 +188,8 @@
   | len == 3   = O.sort3ByOffset cmp a l
   | len == 4   = O.sort4ByOffset cmp a l
   | u <= l + k = sortByBounds cmp a l u
-  | otherwise  = do selectByBounds cmp a k l u
-                    sortHeap cmp a l (l + 4) (l + k)
+  | otherwise  = do selectByBounds cmp a (k + 1) l u
+                    sortHeap cmp a l (l + 4) (l + k + 1)
                     O.sort4ByOffset cmp a l
  where
  len = u - l
diff --git a/tests/properties/Properties.hs b/tests/properties/Properties.hs
--- a/tests/properties/Properties.hs
+++ b/tests/properties/Properties.hs
@@ -97,8 +97,14 @@
 prop_partialsort :: (Ord e, Arbitrary e, Show e)
                  => (forall s mv. G.MVector mv e => mv s e -> Int -> ST s ())
                  -> Positive Int -> Property
-prop_partialsort = prop_sized $ \algo k ->
-  prop_sorted . V.take k . modify algo
+prop_partialsort = prop_sized $ \algo k v -> do
+  let newVec = modify algo v
+      vhead = V.take k newVec
+      vtail = V.drop k newVec
+  prop_sorted vhead
+    .&&.
+      -- Every element in the head should be < every element in the tail.
+      if V.null vtail then 1 == 1 else V.maximum vhead <= V.minimum vtail
 
 prop_sized_empty :: (Ord e) => (forall s. MV.MVector s e -> Int -> ST s ()) -> Property
 prop_sized_empty algo = prop_empty (flip algo 0) .&&. prop_empty (flip algo 10)
diff --git a/vector-algorithms.cabal b/vector-algorithms.cabal
--- a/vector-algorithms.cabal
+++ b/vector-algorithms.cabal
@@ -1,6 +1,6 @@
 cabal-version:     >= 1.10
 name:              vector-algorithms
-version:           0.9.0.2
+version:           0.9.0.3
 license:           BSD3
 license-file:      LICENSE
 author:            Dan Doel
@@ -18,7 +18,9 @@
 extra-source-files: CHANGELOG.md
 
 tested-with:
-  GHC == 9.8.1
+  GHC == 9.12.1
+  GHC == 9.10.1
+  GHC == 9.8.2
   GHC == 9.6.3
   GHC == 9.4.7
   GHC == 9.2.8
@@ -29,7 +31,6 @@
   GHC == 8.4.4
   GHC == 8.2.2
   GHC == 8.0.2
-  GHC == 7.10.3
 
 flag BoundsChecks
   description: Enable bounds checking
@@ -160,7 +161,7 @@
       base >= 4.9,
       bytestring,
       containers,
-      QuickCheck > 2.9 && < 2.15,
+      QuickCheck > 2.9 && < 2.16,
       vector,
       vector-algorithms