diff --git a/concurrent_map.go b/concurrent_map.go
index 6a3e96f..3d40600 100644
--- a/concurrent_map.go
+++ b/concurrent_map.go
@@ -74,6 +74,9 @@ func CreateConcurrentMap(numOfPartitions int) *ConcurrentMap {
 
 func (m *ConcurrentMap) getPartition(key Partitionable) *innerMap {
 	partitionID := key.PartitionKey() % int64(m.numOfBlockets)
+	if partitionID < 0 {
+		partitionID = -partitionID
+	}
 	return (*innerMap)(m.partitions[partitionID])
 }
 
diff --git a/concurrent_map_test.go b/concurrent_map_test.go
index bc8cfa3..da456a5 100644
--- a/concurrent_map_test.go
+++ b/concurrent_map_test.go
@@ -76,3 +76,26 @@ func TestInCurrentEnv(t *testing.T) {
 	}()
 	time.Sleep(time.Second * 1)
 }
+
+
+func TestNegativeInt64KeyBasicOPs(t *testing.T) {
+	for i := 0; i < 10; i++ {
+		testV := rand.Int63n(1024)
+		cm := CreateConcurrentMap(99)
+		var key int64 = -1023
+		v, ok := cm.Get(I64Key(key))
+		if v != nil || ok != false {
+			t.Error("init/get failed")
+		}
+		cm.Set(I64Key(key), testV)
+		v, ok = cm.Get(I64Key(key))
+		if v.(int64) != testV || ok != true {
+			t.Error("set/get failed.")
+		}
+		cm.Del(I64Key(key))
+		v, ok = cm.Get(I64Key(key))
+		if v != nil || ok != false {
+			t.Error("del failed")
+		}
+	}
+}
\ No newline at end of file