diff --git a/t/t9391-filter-repo-lib-usage.sh b/t/t9391-filter-repo-lib-usage.sh
index 1224773..6d670e9 100755
--- a/t/t9391-filter-repo-lib-usage.sh
+++ b/t/t9391-filter-repo-lib-usage.sh
@@ -141,4 +141,14 @@ test_expect_success 'unusual.py' '
 	)
 '
 
+test_expect_success 'erroneous.py' '
+	setup erroneous &&
+	(
+		cd erroneous &&
+		test_must_fail $TEST_DIRECTORY/t9391/erroneous.py 2>../err &&
+
+		test_i18ngrep "Error: Cannot pass a tag_callback to RepoFilter AND pass --tag-callback" ../err
+	)
+'
+
 test_done
diff --git a/t/t9391/erroneous.py b/t/t9391/erroneous.py
new file mode 100755
index 0000000..a5c05d2
--- /dev/null
+++ b/t/t9391/erroneous.py
@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+
+"""
+Please see the
+  ***** API BACKWARD COMPATIBILITY CAVEAT *****
+near the top of git-filter-repo
+"""
+
+import git_filter_repo as fr
+
+def handle_tag(tag):
+  print("Decipher this: "+''.join(reversed(progress.message)))
+
+args = fr.FilteringOptions.parse_args(['--force', '--tag-callback', 'pass'])
+filter = fr.RepoFilter(args, tag_callback = handle_tag)
+filter.run()
diff --git a/t/t9392-python-callback.sh b/t/t9392-python-callback.sh
index 243228f..983879e 100755
--- a/t/t9392-python-callback.sh
+++ b/t/t9392-python-callback.sh
@@ -170,4 +170,15 @@ test_expect_success '--reset-callback' '
 	)
 '
 
+test_expect_success 'callback has return statement sanity check' '
+	setup callback_return_sanity &&
+	(
+		cd callback_return_sanity &&
+
+		test_must_fail git filter-repo --filename-callback "filename + \".txt\"" 2>../err&&
+		test_i18ngrep "Error: --filename-callback should have a return statement" ../err &&
+		rm ../err
+	)
+'
+
 test_done