diff --git a/packages/netlify-cms-backend-git-gateway/src/GitHubAPI.js b/packages/netlify-cms-backend-git-gateway/src/GitHubAPI.js
index eeb5b405..2ba63299 100644
--- a/packages/netlify-cms-backend-git-gateway/src/GitHubAPI.js
+++ b/packages/netlify-cms-backend-git-gateway/src/GitHubAPI.js
@@ -70,22 +70,14 @@ export default class API extends GithubAPI {
     return Promise.resolve(this.commitAuthor);
   }
 
-  request(path, options = {}) {
+  request(path, options = {}, parseResponse = response => this.parseResponse(response)) {
     const url = this.urlFor(path, options);
     let responseStatus;
     return this.getRequestHeaders(options.headers || {})
       .then(headers => fetch(url, { ...options, headers }))
       .then(response => {
         responseStatus = response.status;
-        const contentType = response.headers.get('Content-Type');
-        if (contentType && contentType.match(/json/)) {
-          return this.parseJsonResponse(response);
-        }
-        const text = response.text();
-        if (!response.ok) {
-          return Promise.reject(text);
-        }
-        return text;
+        return parseResponse(response);
       })
       .catch(error => {
         throw new APIError(error.message || error.msg, responseStatus, 'Git Gateway');
diff --git a/packages/netlify-cms-backend-github/src/GraphQLAPI.js b/packages/netlify-cms-backend-github/src/GraphQLAPI.js
index 81770f17..205d3439 100644
--- a/packages/netlify-cms-backend-github/src/GraphQLAPI.js
+++ b/packages/netlify-cms-backend-github/src/GraphQLAPI.js
@@ -186,11 +186,11 @@ export default class GraphQLAPI extends API {
     }
   }
 
-  async listFiles(path) {
-    const { repo_owner: owner, repo_name: name } = this;
+  async listFiles(path, { repoURL = this.repoURL, branch = this.branch } = {}) {
+    const { owner, name } = this.getOwnerAndNameFromRepoUrl(repoURL);
     const { data } = await this.query({
       query: queries.files,
-      variables: { owner, name, expression: `${this.branch}:${path}` },
+      variables: { owner, name, expression: `${branch}:${path}` },
     });
 
     if (data.repository.object) {
diff --git a/packages/netlify-cms-backend-github/src/implementation.js b/packages/netlify-cms-backend-github/src/implementation.js
index f4f9123e..3244bb9b 100644
--- a/packages/netlify-cms-backend-github/src/implementation.js
+++ b/packages/netlify-cms-backend-github/src/implementation.js
@@ -221,14 +221,14 @@ export default class GitHub {
   }
 
   async entriesByFolder(collection, extension) {
-    const repoURL = `/repos/${this.useOpenAuthoring ? this.originRepo : this.repo}`;
+    const repoURL = this.useOpenAuthoring ? this.api.originRepoURL : this.api.repoURL;
     const files = await this.api.listFiles(collection.get('folder'), { repoURL });
     const filteredFiles = files.filter(file => file.name.endsWith('.' + extension));
     return this.fetchFiles(filteredFiles, { repoURL });
   }
 
   entriesByFiles(collection) {
-    const repoURL = `/repos/${this.useOpenAuthoring ? this.originRepo : this.repo}`;
+    const repoURL = this.useOpenAuthoring ? this.api.originRepoURL : this.api.repoURL;
     const files = collection.get('files').map(collectionFile => ({
       path: collectionFile.get('file'),
       label: collectionFile.get('label'),
@@ -236,7 +236,7 @@ export default class GitHub {
     return this.fetchFiles(files, { repoURL });
   }
 
-  fetchFiles = (files, { repoURL = `/repos/${this.repo}` } = {}) => {
+  fetchFiles = (files, { repoURL = this.api.repoURL } = {}) => {
     const sem = semaphore(MAX_CONCURRENT_DOWNLOADS);
     const promises = [];
     files.forEach(file => {
@@ -265,7 +265,7 @@ export default class GitHub {
 
   // Fetches a single entry.
   getEntry(collection, slug, path) {
-    const repoURL = `/repos/${this.originRepo}`;
+    const repoURL = this.api.originRepoURL;
     return this.api.readFile(path, null, { repoURL }).then(data => ({
       file: { path },
       data,