diff --git a/internal/httputil/response.go b/internal/httputil/response.go
index d87161b..1fa275e 100644
--- a/internal/httputil/response.go
+++ b/internal/httputil/response.go
@@ -42,8 +42,8 @@ func NoContent(w http.ResponseWriter) error {
 }
 
 func JSON(w http.ResponseWriter, status int, data interface{}) error {
-	w.WriteHeader(status)
 	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
 
 	if err := json.NewEncoder(w).Encode(data); err != nil {
 		return fmt.Errorf("failed to write json to http response: %w", err)
diff --git a/test/e2e/github_webhook_test.go b/test/e2e/github_webhook_test.go
index f800f14..91a20a7 100644
--- a/test/e2e/github_webhook_test.go
+++ b/test/e2e/github_webhook_test.go
@@ -12,6 +12,7 @@ import (
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	"github.com/tommy351/pullup/internal/fakegithub"
+	"github.com/tommy351/pullup/internal/testutil"
 	"k8s.io/apimachinery/pkg/runtime"
 )
 
@@ -28,7 +29,10 @@ func sendGitHubRequest(event string, data interface{}) {
 		req.Header.Set("X-GitHub-Event", event)
 
 		return http.DefaultClient.Do(req)
-	}).Should(HaveHTTPStatus(http.StatusOK))
+	}).Should(And(
+		HaveHTTPStatus(http.StatusOK),
+		testutil.HaveHTTPHeader("Content-Type", "application/json"),
+	))
 }
 
 var _ = Describe("GitHubWebhook", func() {
diff --git a/test/e2e/http_webhook_test.go b/test/e2e/http_webhook_test.go
index 9349371..fe6ca09 100644
--- a/test/e2e/http_webhook_test.go
+++ b/test/e2e/http_webhook_test.go
@@ -9,6 +9,7 @@ import (
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
+	"github.com/tommy351/pullup/internal/testutil"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/rand"
 )
@@ -40,8 +41,8 @@ var _ = Describe("HTTPWebhook", func() {
 
 			return http.DefaultClient.Do(req)
 		}).Should(And(
-			Not(BeNil()),
 			HaveHTTPStatus(http.StatusOK),
+			testutil.HaveHTTPHeader("Content-Type", "application/json"),
 		))
 	}