diff --git a/eden/scm/edenscm/ext/ghstack/__init__.py b/eden/scm/edenscm/ext/ghstack/__init__.py
index df06dea582..7b2fa1e43b 100644
--- a/eden/scm/edenscm/ext/ghstack/__init__.py
+++ b/eden/scm/edenscm/ext/ghstack/__init__.py
@@ -262,6 +262,7 @@ query UsernameQuery {
     user_name, user_email = gituser.get_identity_or_raise(ui)
     sh = ghstack.sapling_shell.SaplingShell(
         conf=conf,
+        ui=ui,
         git_dir=git_dir,
         user_name=user_name,
         user_email=user_email,
diff --git a/eden/scm/ghstack/sapling_shell.py b/eden/scm/ghstack/sapling_shell.py
index 74ce57a162..2153b06a5a 100644
--- a/eden/scm/ghstack/sapling_shell.py
+++ b/eden/scm/ghstack/sapling_shell.py
@@ -3,6 +3,7 @@ import logging
 import os
 from typing import Any, Dict, Optional, List
 
+from edenscm import gpg
 import ghstack
 import ghstack.config
 from ghstack.ghs_types import GitCommitHash
@@ -14,6 +15,7 @@ class SaplingShell(ghstack.shell.Shell):
     def __init__(self,
                  *,
                  conf: ghstack.config.Config,
+                 ui = None,  # Sapling ui object.
                  git_dir: str,
                  user_name: str,
                  user_email: str,
@@ -32,6 +34,7 @@ class SaplingShell(ghstack.shell.Shell):
         """
         super().__init__(quiet=quiet, cwd=cwd, testing=testing)
         self.conf = conf
+        self.ui = ui
         self.git_dir = git_dir
         self.user_name = user_name
         self.user_email = user_email
@@ -132,7 +135,9 @@ class SaplingShell(ghstack.shell.Shell):
         """Run `git commit-tree`, adding GPG flags, if appropriate.
         """
         config_flags = ['-c', f'user.name={self.user_name}', '-c', f'user.email={self.user_email}']
-        full_args = config_flags + ["commit-tree"] + list(args)
+        keyid = gpg.get_gpg_keyid(self.ui)
+        gpg_args = [f'-S{keyid}'] if keyid else []
+        full_args = config_flags + ["commit-tree"] + gpg_args + list(args)
         stdout = self.git(*full_args, **kwargs)
         if isinstance(stdout, str):
             return GitCommitHash(stdout)
diff --git a/eden/scm/ghstack/shell.py b/eden/scm/ghstack/shell.py
index a3e8b52535..184b10cb79 100644
--- a/eden/scm/ghstack/shell.py
+++ b/eden/scm/ghstack/shell.py
@@ -287,14 +287,10 @@ class Shell(object):
             ) -> GitCommitHash:
         """Run `git commit-tree`, adding GPG flags, if appropriate.
         """
-        gpg_args = self.get_gpg_args()
+        gpg_args = gpg_args_if_necessary(self)
         full_args = ["commit-tree"] + gpg_args + list(args)
         return GitCommitHash(self.git(*full_args, **kwargs))
 
-    def get_gpg_args(self) -> List[str]:
-        """args to include with `git commit` or `git commit-tree` for GPG signing"""
-        return gpg_args_if_necessary(self)
-
     @overload  # noqa: F811
     def hg(self, *args: str) -> str:
         ...