diff --git a/packages/netlify-cms-backend-git-gateway/src/implementation.js b/packages/netlify-cms-backend-git-gateway/src/implementation.js
index f9606c6e..97e7e7dd 100644
--- a/packages/netlify-cms-backend-git-gateway/src/implementation.js
+++ b/packages/netlify-cms-backend-git-gateway/src/implementation.js
@@ -315,6 +315,9 @@ export default class GitGateway {
       if (client.enabled && client.matchPath(path)) {
         return client.getDownloadURL(largeMediaDisplayURL);
       }
+      if (typeof original === 'string') {
+        return original;
+      }
       if (this.backend.getMediaDisplayURL) {
         return this.backend.getMediaDisplayURL(original);
       }