diff --git a/cli/compose/loader/merge.go b/cli/compose/loader/merge.go
index a321fd18c..002b4c776 100644
--- a/cli/compose/loader/merge.go
+++ b/cli/compose/loader/merge.go
@@ -116,7 +116,11 @@ func toServicePortConfigsMap(s any) (map[any]any, error) {
 	}
 	m := map[any]any{}
 	for _, p := range ports {
-		m[p.Published] = p
+		protocol := "tcp"
+		if p.Protocol != "" {
+			protocol = p.Protocol
+		}
+		m[fmt.Sprintf("%d%s", p.Published, protocol)] = p
 	}
 	return m, nil
 }
diff --git a/cli/compose/loader/merge_test.go b/cli/compose/loader/merge_test.go
index 40445d6c4..fbe987310 100644
--- a/cli/compose/loader/merge_test.go
+++ b/cli/compose/loader/merge_test.go
@@ -848,6 +848,8 @@ func TestLoadMultipleConfigs(t *testing.T) {
 				"ports": []any{
 					"8080:80",
 					"9090:90",
+					"53:53/tcp",
+					"53:53/udp",
 				},
 				"labels": []any{
 					"foo=bar",
@@ -925,6 +927,18 @@ func TestLoadMultipleConfigs(t *testing.T) {
 					},
 				},
 				Ports: []types.ServicePortConfig{
+					{
+						Mode:      "ingress",
+						Target:    53,
+						Published: 53,
+						Protocol:  "tcp",
+					},
+					{
+						Mode:      "ingress",
+						Target:    53,
+						Published: 53,
+						Protocol:  "udp",
+					},
 					{
 						Target:    81,
 						Published: 8080,