diff --git a/freelist_hmap.go b/freelist_hmap.go
index 02ef2be04..64aeb8199 100644
--- a/freelist_hmap.go
+++ b/freelist_hmap.go
@@ -76,12 +76,21 @@ func (f *freelist) hashmapGetFreePageIDs() []pgid {
 	}
 
 	m := make([]pgid, 0, count)
-	for start, size := range f.forwardMap {
-		for i := 0; i < int(size); i++ {
-			m = append(m, start+pgid(i))
+
+	keys := make([]pgid, 0, len(f.forwardMap))
+	for k := range f.forwardMap {
+		keys = append(keys, k)
+	}
+	sort.Sort(pgids(keys))
+
+	for _, start := range keys {
+		size, ok := f.forwardMap[start]
+		if ok {
+			for i := 0; i < int(size); i++ {
+				m = append(m, start+pgid(i))
+			}
 		}
 	}
-	sort.Sort(pgids(m))
 
 	return m
 }
diff --git a/freelist_test.go b/freelist_test.go
index 97656f4a2..eb546c746 100644
--- a/freelist_test.go
+++ b/freelist_test.go
@@ -432,3 +432,27 @@ func newTestFreelist() *freelist {
 
 	return newFreelist(freelistType)
 }
+
+func Test_freelist_hashmapGetFreePageIDs(t *testing.T) {
+	f := newTestFreelist()
+	if f.freelistType == FreelistArrayType {
+		t.Skip()
+	}
+
+	N := int32(100000)
+	fm := make(map[pgid]uint64)
+	i := int32(0)
+	val := int32(0)
+	for i = 0; i < N; {
+		val = rand.Int31n(1000)
+		fm[pgid(i)] = uint64(val)
+		i += val
+	}
+
+	f.forwardMap = fm
+	res := f.hashmapGetFreePageIDs()
+
+	if !sort.SliceIsSorted(res, func(i, j int) bool { return res[i] < res[j] }) {
+		t.Fatalf("pgids not sorted")
+	}
+}