diff --git a/bumpversion/vcs.py b/bumpversion/vcs.py
index c5516f4..6538234 100644
--- a/bumpversion/vcs.py
+++ b/bumpversion/vcs.py
@@ -67,7 +67,9 @@ def assert_nondirty(cls):
 
         if lines:
             raise WorkingDirectoryIsDirtyException(
-                "Git working directory is not clean:\n{}".format(b"\n".join(lines))
+                "Git working directory is not clean:\n{}".format(
+                    b"\n".join(lines).decode()
+                )
             )
 
     @classmethod
@@ -143,7 +145,7 @@ def assert_nondirty(cls):
         if lines:
             raise WorkingDirectoryIsDirtyException(
                 "Mercurial working directory is not clean:\n{}".format(
-                    b"\n".join(lines)
+                    b"\n".join(lines).decode()
                 )
             )
 
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 28aacad..5b5addf 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -412,7 +412,7 @@ def test_dirty_work_dir(tmpdir, vcs):
 
     check_call([vcs, "add", "dirty"])
     vcs_name = "Mercurial" if vcs == "hg" else "Git"
-    vcs_output = "b'A dirty'" if vcs == "hg" else "b'A  dirty'"
+    vcs_output = "A dirty" if vcs == "hg" else "A  dirty"
 
     with pytest.raises(WorkingDirectoryIsDirtyException):
         with LogCapture() as log_capture: