diff --git a/Octokit/Models/Response/PullRequest.cs b/Octokit/Models/Response/PullRequest.cs
index 735cf9dd..e326bd36 100644
--- a/Octokit/Models/Response/PullRequest.cs
+++ b/Octokit/Models/Response/PullRequest.cs
@@ -105,7 +105,7 @@ namespace Octokit
         /// <summary>
         /// Whether or not the pull request can be merged.
         /// </summary>
-        public bool Mergeable { get; set; }
+        public bool? Mergeable { get; set; }
 
         /// <summary>
         /// The user who merged the pull request.