diff --git a/internal/istiooperator/istiooperator_test.go b/internal/istiooperator/istiooperator_test.go
index 2fd40d773a..c59bcc70d7 100644
--- a/internal/istiooperator/istiooperator_test.go
+++ b/internal/istiooperator/istiooperator_test.go
@@ -1,9 +1,9 @@
 package istiooperator_test
 
 import (
-	"encoding/json"
 	meshv1alpha1 "istio.io/api/mesh/v1alpha1"
 	"istio.io/istio/operator/pkg/values"
+	"istio.io/istio/pkg/util/protomarshal"
 	"os"
 	"path"
 	"regexp"
@@ -82,8 +82,7 @@ var _ = Describe("Merge", func() {
 
 			var meshConfigTyped meshv1alpha1.MeshConfig
 
-			meshConfigSnakeCase := jsonTagsToSnakeCase(iop.Spec.MeshConfig)
-			err = json.Unmarshal([]byte(meshConfigSnakeCase), &meshConfigTyped)
+			err = protomarshal.Unmarshal(iop.Spec.MeshConfig, &meshConfigTyped)
 			Expect(err).ShouldNot(HaveOccurred())
 
 			numTrustedProxies := meshConfigTyped.DefaultConfig.GetGatewayTopology().GetNumTrustedProxies()
@@ -131,9 +130,8 @@ var _ = Describe("Merge", func() {
 		iop := readIOP(mergedIstioOperatorPath)
 
 		var typedMeshConfig meshv1alpha1.MeshConfig
-		snakeCaseMeshConfig := jsonTagsToSnakeCase(iop.Spec.MeshConfig)
 
-		err = json.Unmarshal([]byte(snakeCaseMeshConfig), &typedMeshConfig)
+		err = protomarshal.Unmarshal(iop.Spec.MeshConfig, &typedMeshConfig)
 		Expect(err).ShouldNot(HaveOccurred())
 
 		numTrustedProxies := typedMeshConfig.DefaultConfig.GetGatewayTopology().GetNumTrustedProxies()