diff --git a/lib/api/files.rb b/lib/api/files.rb
index 4b3280a98b4..ff4f75c12df 100644
--- a/lib/api/files.rb
+++ b/lib/api/files.rb
@@ -59,7 +59,7 @@ module API
       params :simple_file_params do
         requires :file_path, type: String, desc: 'The url encoded path to the file. Ex. lib%2Fclass%2Erb'
         requires :branch, type: String, desc: 'Name of the branch to commit into. To create a new branch, also provide `start_branch`.'
-        requires :commit_message, type: String, regexp: /^\S+$/, desc: 'Commit message'
+        requires :commit_message, type: String, allow_blank: false, desc: 'Commit message'
         optional :start_branch, type: String, desc: 'Name of the branch to start the new commit from'
         optional :author_email, type: String, desc: 'The email of the author'
         optional :author_name, type: String, desc: 'The name of the author'
diff --git a/spec/requests/api/files_spec.rb b/spec/requests/api/files_spec.rb
index 20992362b8c..d797a20d8a1 100644
--- a/spec/requests/api/files_spec.rb
+++ b/spec/requests/api/files_spec.rb
@@ -313,7 +313,7 @@ describe API::Files do
 
   describe "POST /projects/:id/repository/files/:file_path" do
     let!(:file_path) { "new_subfolder%2Fnewfile%2Erb" }
-    let(:valid_params) do
+    let(:params) do
       {
         branch: "master",
         content: "puts 8",
@@ -322,7 +322,7 @@ describe API::Files do
     end
 
     it "creates a new file in project repo" do
-      post api(route(file_path), user), valid_params
+      post api(route(file_path), user), params
 
       expect(response).to have_gitlab_http_status(201)
       expect(json_response["file_path"]).to eq(CGI.unescape(file_path))
@@ -338,13 +338,9 @@ describe API::Files do
     end
 
     it 'returns a 400 bad request if the commit message is empty' do
-      invalid_params = {
-        branch: 'master',
-        content: 'puts 8',
-        commit_message: ''
-      }
+      params[:commit_message] = ''
 
-      post api(route(file_path), user), invalid_params
+      post api(route(file_path), user), params
 
       expect(response).to have_gitlab_http_status(400)
     end
@@ -353,16 +349,16 @@ describe API::Files do
       allow_any_instance_of(Repository).to receive(:create_file)
         .and_raise(Gitlab::Git::CommitError, 'Cannot create file')
 
-      post api(route("any%2Etxt"), user), valid_params
+      post api(route("any%2Etxt"), user), params
 
       expect(response).to have_gitlab_http_status(400)
     end
 
     context "when specifying an author" do
       it "creates a new file with the specified author" do
-        valid_params.merge!(author_email: author_email, author_name: author_name)
+        params.merge!(author_email: author_email, author_name: author_name)
 
-        post api(route("new_file_with_author%2Etxt"), user), valid_params
+        post api(route("new_file_with_author%2Etxt"), user), params
 
         expect(response).to have_gitlab_http_status(201)
         expect(response.content_type).to eq('application/json')
@@ -376,7 +372,7 @@ describe API::Files do
       let!(:project) { create(:project_empty_repo, namespace: user.namespace ) }
 
       it "creates a new file in project repo" do
-        post api(route("newfile%2Erb"), user), valid_params
+        post api(route("newfile%2Erb"), user), params
 
         expect(response).to have_gitlab_http_status(201)
         expect(json_response['file_path']).to eq('newfile.rb')
@@ -388,7 +384,7 @@ describe API::Files do
   end
 
   describe "PUT /projects/:id/repository/files" do
-    let(:valid_params) do
+    let(:params) do
       {
         branch: 'master',
         content: 'puts 8',
@@ -397,7 +393,7 @@ describe API::Files do
     end
 
     it "updates existing file in project repo" do
-      put api(route(file_path), user), valid_params
+      put api(route(file_path), user), params
 
       expect(response).to have_gitlab_http_status(200)
       expect(json_response['file_path']).to eq(CGI.unescape(file_path))
@@ -406,8 +402,16 @@ describe API::Files do
       expect(last_commit.author_name).to eq(user.name)
     end
 
+    it 'returns a 400 bad request if the commit message is empty' do
+      params[:commit_message] = ''
+
+      put api(route(file_path), user), params
+
+      expect(response).to have_gitlab_http_status(400)
+    end
+
     it "returns a 400 bad request if update existing file with stale last commit id" do
-      params_with_stale_id = valid_params.merge(last_commit_id: 'stale')
+      params_with_stale_id = params.merge(last_commit_id: 'stale')
 
       put api(route(file_path), user), params_with_stale_id
 
@@ -418,7 +422,7 @@ describe API::Files do
     it "updates existing file in project repo with accepts correct last commit id" do
       last_commit = Gitlab::Git::Commit
                         .last_for_path(project.repository, 'master', URI.unescape(file_path))
-      params_with_correct_id = valid_params.merge(last_commit_id: last_commit.id)
+      params_with_correct_id = params.merge(last_commit_id: last_commit.id)
 
       put api(route(file_path), user), params_with_correct_id
 
@@ -433,9 +437,9 @@ describe API::Files do
 
     context "when specifying an author" do
       it "updates a file with the specified author" do
-        valid_params.merge!(author_email: author_email, author_name: author_name, content: "New content")
+        params.merge!(author_email: author_email, author_name: author_name, content: "New content")
 
-        put api(route(file_path), user), valid_params
+        put api(route(file_path), user), params
 
         expect(response).to have_gitlab_http_status(200)
         last_commit = project.repository.commit.raw