diff --git a/github_backup/github_backup.py b/github_backup/github_backup.py
index 178da62..839435b 100644
--- a/github_backup/github_backup.py
+++ b/github_backup/github_backup.py
@@ -419,7 +419,13 @@ def get_github_host(args):
 
 def get_github_repo_url(args, repository):
     if repository.get('is_gist'):
-        return repository['git_pull_url']
+        if args.prefer_ssh:
+            # The git_pull_url value is always https for gists, so we need to transform it to ssh form
+            repo_url = re.sub('^https?:\/\/(.+)\/(.+)\.git$', r'git@\1:\2.git', repository['git_pull_url'])
+            repo_url = re.sub('^git@gist\.', 'git@', repo_url) # strip gist subdomain for better hostkey compatibility
+        else:
+            repo_url = repository['git_pull_url']
+        return repo_url
 
     if args.prefer_ssh:
         return repository['ssh_url']