diff --git a/lib/common/tests/strings/pcmk__parse_ll_range_test.c b/lib/common/tests/strings/pcmk__parse_ll_range_test.c
index 2204be8e3a..5ec020f69b 100644
--- a/lib/common/tests/strings/pcmk__parse_ll_range_test.c
+++ b/lib/common/tests/strings/pcmk__parse_ll_range_test.c
@@ -1,114 +1,124 @@
 /*
- * Copyright 2020-2021 the Pacemaker project contributors
+ * Copyright 2020-2022 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
 
 #include <crm_internal.h>
 
 #include <crm/common/unittest_internal.h>
 
 static void
 empty_input_string(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range(NULL, &start, &end), pcmk_rc_unknown_format);
     assert_int_equal(pcmk__parse_ll_range("", &start, &end), pcmk_rc_unknown_format);
 }
 
+static void
+null_input_variables(void **state)
+{
+    long long start, end;
+
+    pcmk__assert_asserts(pcmk__parse_ll_range("1234", NULL, &end));
+    pcmk__assert_asserts(pcmk__parse_ll_range("1234", &start, NULL));
+}
+
 static void
 missing_separator(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range("1234", &start, &end), pcmk_rc_ok);
     assert_int_equal(start, 1234);
     assert_int_equal(end, 1234);
 }
 
 static void
 only_separator(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range("-", &start, &end), pcmk_rc_unknown_format);
     assert_int_equal(start, PCMK__PARSE_INT_DEFAULT);
     assert_int_equal(end, PCMK__PARSE_INT_DEFAULT);
 }
 
 static void
 no_range_end(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range("2000-", &start, &end), pcmk_rc_ok);
     assert_int_equal(start, 2000);
     assert_int_equal(end, PCMK__PARSE_INT_DEFAULT);
 }
 
 static void
 no_range_start(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range("-2020", &start, &end), pcmk_rc_ok);
     assert_int_equal(start, PCMK__PARSE_INT_DEFAULT);
     assert_int_equal(end, 2020);
 }
 
 static void
 range_start_and_end(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range("2000-2020", &start, &end), pcmk_rc_ok);
     assert_int_equal(start, 2000);
     assert_int_equal(end, 2020);
 
     assert_int_equal(pcmk__parse_ll_range("2000-2020-2030", &start, &end), pcmk_rc_unknown_format);
 }
 
 static void
 garbage(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range("2000x-", &start, &end), pcmk_rc_unknown_format);
     assert_int_equal(start, PCMK__PARSE_INT_DEFAULT);
     assert_int_equal(end, PCMK__PARSE_INT_DEFAULT);
 
     assert_int_equal(pcmk__parse_ll_range("-x2000", &start, &end), pcmk_rc_unknown_format);
     assert_int_equal(start, PCMK__PARSE_INT_DEFAULT);
     assert_int_equal(end, PCMK__PARSE_INT_DEFAULT);
 }
 
 static void
 strtoll_errors(void **state)
 {
     long long start, end;
 
     assert_int_equal(pcmk__parse_ll_range("20000000000000000000-", &start, &end), pcmk_rc_unknown_format);
     assert_int_equal(pcmk__parse_ll_range("100-20000000000000000000", &start, &end), pcmk_rc_unknown_format);
 }
 
 int main(int argc, char **argv)
 {
     const struct CMUnitTest tests[] = {
         cmocka_unit_test(empty_input_string),
+        cmocka_unit_test(null_input_variables),
         cmocka_unit_test(missing_separator),
         cmocka_unit_test(only_separator),
         cmocka_unit_test(no_range_end),
         cmocka_unit_test(no_range_start),
         cmocka_unit_test(range_start_and_end),
         cmocka_unit_test(strtoll_errors),
 
         cmocka_unit_test(garbage),
     };
 
     cmocka_set_message_output(CM_OUTPUT_TAP);
     return cmocka_run_group_tests(tests, NULL, NULL);
 }