diff --git a/server/handler/badge.go b/server/handler/badge.go
index 173e3846..3dcd6229 100644
--- a/server/handler/badge.go
+++ b/server/handler/badge.go
@@ -113,6 +113,8 @@ func GetCC(c web.C, w http.ResponseWriter, r *http.Request) {
 		name  = c.URLParams["name"]
 	)
 
+	w.Header().Set("Content-Type", "application/xml")
+
 	repo, err := datastore.GetRepoName(ctx, host, owner, name)
 	if err != nil {
 		w.WriteHeader(http.StatusNotFound)
diff --git a/server/handler/login.go b/server/handler/login.go
index 2ae13603..2b188bea 100644
--- a/server/handler/login.go
+++ b/server/handler/login.go
@@ -30,6 +30,8 @@ func GetLogin(c web.C, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	w.Header().Del("Content-Type")
+
 	// authenticate the user
 	login, err := remote.Authorize(w, r)
 	if err != nil {
diff --git a/server/handler/output.go b/server/handler/output.go
index 21a1e037..28cca8d1 100644
--- a/server/handler/output.go
+++ b/server/handler/output.go
@@ -24,6 +24,8 @@ func GetOutput(c web.C, w http.ResponseWriter, r *http.Request) {
 		hash   = c.URLParams["commit"]
 	)
 
+	w.Header().Set("Content-Type", "text/plain")
+
 	path := filepath.Join(host, owner, name, branch, hash)
 	rc, err := blobstore.GetReader(ctx, path)
 	if err != nil {
diff --git a/server/middleware/options.go b/server/middleware/options.go
index 42aefc77..24a78902 100644
--- a/server/middleware/options.go
+++ b/server/middleware/options.go
@@ -15,6 +15,7 @@ func Options(c *web.C, h http.Handler) http.Handler {
 			w.Header().Set("Access-Control-Allow-Methods", "GET,POST,PUT,DELETE,OPTIONS")
 			w.Header().Set("Access-Control-Allow-Headers", "Authorization")
 			w.Header().Set("Allow", "HEAD,GET,POST,PUT,DELETE,OPTIONS")
+			w.Header().Set("Content-Type", "application/json")
 			w.WriteHeader(http.StatusOK)
 			return
 		}