diff --git a/aider/repo.py b/aider/repo.py
index 8b4cf9428..5b9d0b7d1 100644
--- a/aider/repo.py
+++ b/aider/repo.py
@@ -206,11 +206,16 @@ class GitRepo:
         if not self.aider_ignore_file or not self.aider_ignore_file.is_file():
             return fnames
 
-        lines = self.aider_ignore_file.read_text().splitlines()
-        self.aider_ignore_spec = pathspec.PathSpec.from_lines(
-            pathspec.patterns.GitWildMatchPattern,
-            lines,
-        )
+        mtime = self.aider_ignore_file.stat().st_mtime
+        dump(mtime)
+
+        if mtime != self.aider_ignore_ts:
+            self.aider_ignore_ts = mtime
+            lines = self.aider_ignore_file.read_text().splitlines()
+            self.aider_ignore_spec = pathspec.PathSpec.from_lines(
+                pathspec.patterns.GitWildMatchPattern,
+                lines,
+            )
 
         return [fname for fname in fnames if not self.aider_ignore_spec.match_file(fname)]
 
diff --git a/tests/test_repo.py b/tests/test_repo.py
index fcfde5f00..43fb9212f 100644
--- a/tests/test_repo.py
+++ b/tests/test_repo.py
@@ -204,6 +204,7 @@ class TestRepo(unittest.TestCase):
             self.assertIn(str(fname2), fnames)
 
             aiderignore.write_text("new.txt\n")
+            dump(aiderignore.read_text())
 
             # new.txt should be gone!
             fnames = git_repo.get_tracked_files()
@@ -211,6 +212,7 @@ class TestRepo(unittest.TestCase):
             self.assertIn(str(fname2), fnames)
 
             aiderignore.write_text("new2.txt\n")
+            dump(aiderignore.read_text())
 
             # new2.txt should be gone!
             fnames = git_repo.get_tracked_files()