diff --git a/routers/api/v1/repo/file.go b/routers/api/v1/repo/file.go
index 90a84cd54..d409a2848 100644
--- a/routers/api/v1/repo/file.go
+++ b/routers/api/v1/repo/file.go
@@ -199,6 +199,10 @@ func CreateFile(ctx *context.APIContext, apiOpts api.CreateFileOptions) {
 	//   "201":
 	//     "$ref": "#/responses/FileResponse"
 
+	if apiOpts.BranchName == "" {
+		apiOpts.BranchName = ctx.Repo.Repository.DefaultBranch
+	}
+
 	opts := &repofiles.UpdateRepoFileOptions{
 		Content:   apiOpts.Content,
 		IsNewFile: true,
@@ -271,6 +275,10 @@ func UpdateFile(ctx *context.APIContext, apiOpts api.UpdateFileOptions) {
 	//   "200":
 	//     "$ref": "#/responses/FileResponse"
 
+	if apiOpts.BranchName == "" {
+		apiOpts.BranchName = ctx.Repo.Repository.DefaultBranch
+	}
+
 	opts := &repofiles.UpdateRepoFileOptions{
 		Content:      apiOpts.Content,
 		SHA:          apiOpts.SHA,
@@ -377,6 +385,10 @@ func DeleteFile(ctx *context.APIContext, apiOpts api.DeleteFileOptions) {
 		return
 	}
 
+	if apiOpts.BranchName == "" {
+		apiOpts.BranchName = ctx.Repo.Repository.DefaultBranch
+	}
+
 	opts := &repofiles.DeleteRepoFileOptions{
 		Message:   apiOpts.Message,
 		OldBranch: apiOpts.BranchName,