diff --git a/nbstripout/_nbstripout.py b/nbstripout/_nbstripout.py
index 7168e39..41dfe4d 100644
--- a/nbstripout/_nbstripout.py
+++ b/nbstripout/_nbstripout.py
@@ -378,6 +378,9 @@ def process_jupyter_notebook(
     )
 
     any_change = nb_orig != nb_stripped
+    # Early exit when writing in-place and nothing changes.
+    if not any_change and output_stream is input_stream:
+        return any_change
 
     if args.dry_run:
         if any_change:
@@ -410,6 +413,9 @@ def process_zeppelin_notebook(
     nb_stripped = strip_zeppelin_output(nb)
 
     any_change = nb_orig != nb_stripped
+    # Early exit when writing in-place and nothing changes.
+    if not any_change and output_stream is input_stream:
+        return any_change
 
     if args.dry_run:
         if any_change:
diff --git a/tests/test_end_to_end.py b/tests/test_end_to_end.py
index 555b843..f0bfb83 100644
--- a/tests/test_end_to_end.py
+++ b/tests/test_end_to_end.py
@@ -184,3 +184,21 @@ def test_make_errors(input_file: str, expected_errs: List[Union[str, Pattern]],
             assert e.search(err_output)
         else:
             assert e in err_output
+
+
+def test_nochange_notebook_unchanged():
+    ipynb_file = NOTEBOOKS_FOLDER / 'test_nochange.ipynb'
+    ipynb_mtime_before = ipynb_file.stat().st_mtime_ns
+
+    run([nbstripout_exe(), ipynb_file])
+    ipynb_mtime_after = ipynb_file.stat().st_mtime_ns
+
+    assert ipynb_mtime_after == ipynb_mtime_before
+
+    zpln_file = NOTEBOOKS_FOLDER / 'test_zeppelin.zpln.expected'
+    zpln_mtime_before = zpln_file.stat().st_mtime_ns
+
+    run([nbstripout_exe(), '--force', '--mode', 'zeppelin', zpln_file])
+    zpln_mtime_after = zpln_file.stat().st_mtime_ns
+
+    assert zpln_mtime_after == zpln_mtime_before