diff --git a/pkg/transformers/json/transformer.go b/pkg/transformers/json/transformer.go
index 0421ebf20e..f15f60383c 100644
--- a/pkg/transformers/json/transformer.go
+++ b/pkg/transformers/json/transformer.go
@@ -44,6 +44,9 @@ func transformer(msg messaging.Message) (interface{}, error) {
 		Channel:   msg.Channel,
 		Subtopic:  msg.Subtopic,
 	}
+	if ret.Subtopic == "" {
+		return nil, errors.Wrap(ErrTransform, errUnknownFormat)
+	}
 	subs := strings.Split(ret.Subtopic, ".")
 	if len(subs) == 0 {
 		return nil, errors.Wrap(ErrTransform, errUnknownFormat)
diff --git a/pkg/transformers/json/transformer_test.go b/pkg/transformers/json/transformer_test.go
index 809c284724..89e39f2ce4 100644
--- a/pkg/transformers/json/transformer_test.go
+++ b/pkg/transformers/json/transformer_test.go
@@ -56,6 +56,9 @@ func TestTransformJSON(t *testing.T) {
 		Format: msg.Subtopic,
 	}
 
+	invalidFmt := msg
+	invalidFmt.Subtopic = ""
+
 	listJSON := json.Messages{
 		Data: []json.Message{
 			{
@@ -100,6 +103,12 @@ func TestTransformJSON(t *testing.T) {
 			json: jsonMsg,
 			err:  nil,
 		},
+		{
+			desc: "test transform JSON with an invalid subtopic",
+			msg:  invalidFmt,
+			json: nil,
+			err:  json.ErrTransform,
+		},
 		{
 			desc: "test transform JSON array",
 			msg:  listMsg,