diff --git a/pre_commit/util.py b/pre_commit/util.py
index 3d448e31..ea0d4f52 100644
--- a/pre_commit/util.py
+++ b/pre_commit/util.py
@@ -62,7 +62,7 @@ class CalledProcessError(RuntimeError):
     def __bytes__(self) -> bytes:
         def _indent_or_none(part: bytes | None) -> bytes:
             if part:
-                return b'\n    ' + part.replace(b'\n', b'\n    ')
+                return b'\n    ' + part.replace(b'\n', b'\n    ').rstrip()
             else:
                 return b' (none)'
 
diff --git a/tests/staged_files_only_test.py b/tests/staged_files_only_test.py
index 50f146be..58dbe5ac 100644
--- a/tests/staged_files_only_test.py
+++ b/tests/staged_files_only_test.py
@@ -425,9 +425,7 @@ def test_failed_diff_does_not_discard_changes(in_git_dir, patch_dir):
         r'stdout: \(none\)\n'
         r'stderr:\n'
         r'    error: open\("1"\): Permission denied\n'
-        r'    fatal: cannot hash 1\n'
-        # TODO: not sure why there's weird whitespace here
-        r'    $',
+        r'    fatal: cannot hash 1$',
     ).assert_matches(msg)
 
     # even though it errored, the unstaged changes should still be present
diff --git a/tests/util_test.py b/tests/util_test.py
index 310f8f58..5b262113 100644
--- a/tests/util_test.py
+++ b/tests/util_test.py
@@ -16,7 +16,7 @@ from pre_commit.util import rmtree
 
 
 def test_CalledProcessError_str():
-    error = CalledProcessError(1, ('exe',), b'output', b'errors')
+    error = CalledProcessError(1, ('exe',), b'output\n', b'errors\n')
     assert str(error) == (
         "command: ('exe',)\n"
         'return code: 1\n'