diff --git a/ogr/abstract/pull_request.py b/ogr/abstract/pull_request.py
index 8a20fc3d..8563534c 100644
--- a/ogr/abstract/pull_request.py
+++ b/ogr/abstract/pull_request.py
@@ -78,7 +78,9 @@ def created(self) -> datetime.datetime:
 
     @property
     def labels(self) -> Union[list["_abstract.PRLabel"], Iterable["_abstract.PRLabel"]]:
-        """Labels of the pull request."""
+        """
+        Labels of the pull request. Cached, may be outdated if modified externally.
+        """
         raise NotImplementedError()
 
     @property
diff --git a/ogr/services/github/pull_request.py b/ogr/services/github/pull_request.py
index 0d778efa..025092ec 100644
--- a/ogr/services/github/pull_request.py
+++ b/ogr/services/github/pull_request.py
@@ -28,6 +28,7 @@ class GithubPullRequest(BasePullRequest):
     _raw_pr: _GithubPullRequest
     _target_project: "ogr_github.GithubProject"
     _source_project: "ogr_github.GithubProject" = None
+    _labels: list[PRLabel] = None
 
     @property
     def title(self) -> str:
@@ -79,9 +80,12 @@ def created(self) -> datetime.datetime:
 
     @property
     def labels(self) -> list[PRLabel]:
-        return [
-            GithubPRLabel(raw_label, self) for raw_label in self._raw_pr.get_labels()
-        ]
+        if not self._labels:
+            self._labels = [
+                GithubPRLabel(raw_label, self)
+                for raw_label in self._raw_pr.get_labels()
+            ]
+        return self._labels
 
     @property
     def diff_url(self) -> str:
@@ -265,6 +269,9 @@ def merge(self) -> "PullRequest":
     def add_label(self, *labels: str) -> None:
         for label in labels:
             self._raw_pr.add_to_labels(label)
+        self._labels = [
+            GithubPRLabel(raw_label, self) for raw_label in self._raw_pr.get_labels()
+        ]
 
     def get_comment(self, comment_id: int) -> PRComment:
         return GithubPRComment(self._raw_pr.get_issue_comment(comment_id))