diff --git a/core/mapping/unmarshaler.go b/core/mapping/unmarshaler.go
index f8674211..d19469f3 100644
--- a/core/mapping/unmarshaler.go
+++ b/core/mapping/unmarshaler.go
@@ -289,6 +289,10 @@ func (u *Unmarshaler) generateMap(keyType, elemType reflect.Type, mapValue any)
 		return reflect.ValueOf(mapValue), nil
 	}
 
+	if keyType != valueType.Key() {
+		return emptyValue, errTypeMismatch
+	}
+
 	refValue := reflect.ValueOf(mapValue)
 	targetValue := reflect.MakeMapWithSize(mapType, refValue.Len())
 	dereffedElemType := Deref(elemType)
diff --git a/core/mapping/unmarshaler_test.go b/core/mapping/unmarshaler_test.go
index cdd7b98a..4b6148a2 100644
--- a/core/mapping/unmarshaler_test.go
+++ b/core/mapping/unmarshaler_test.go
@@ -4437,3 +4437,18 @@ func TestFillDefaultUnmarshal(t *testing.T) {
 		assert.Error(t, err)
 	})
 }
+
+func Test_UnmarshalMap(t *testing.T) {
+	type Customer struct {
+		Names map[int]string `key:"names"`
+	}
+
+	input := map[string]any{
+		"names": map[string]any{
+			"19": "Tom",
+		},
+	}
+
+	var customer Customer
+	assert.ErrorIs(t, UnmarshalKey(input, &customer), errTypeMismatch)
+}