diff --git a/lib/common/tests/strings/pcmk__guint_from_hash_test.c b/lib/common/tests/strings/pcmk__guint_from_hash_test.c
index e2b476217b..225c5b36c5 100644
--- a/lib/common/tests/strings/pcmk__guint_from_hash_test.c
+++ b/lib/common/tests/strings/pcmk__guint_from_hash_test.c
@@ -1,76 +1,80 @@
 /*
  * Copyright 2022 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU General Public License version 2
  * or later (GPLv2+) WITHOUT ANY WARRANTY.
  */
 
 #include <crm_internal.h>
 
 #include <crm/common/unittest_internal.h>
 
 #include <glib.h>
 
 static void
 null_args(void **state)
 {
     GHashTable *tbl = pcmk__strkey_table(free, free);
     guint result;
 
     assert_int_equal(pcmk__guint_from_hash(NULL, "abc", 123, &result), EINVAL);
     assert_int_equal(pcmk__guint_from_hash(tbl, NULL, 123, &result), EINVAL);
 
     g_hash_table_destroy(tbl);
 }
 
 static void
 missing_key(void **state)
 {
     GHashTable *tbl = pcmk__strkey_table(free, free);
     guint result;
 
     assert_int_equal(pcmk__guint_from_hash(tbl, "abc", 123, &result), pcmk_rc_ok);
     assert_int_equal(result, 123);
 
     g_hash_table_destroy(tbl);
 }
 
 static void
 standard_usage(void **state)
 {
     GHashTable *tbl = pcmk__strkey_table(free, free);
     guint result;
 
     g_hash_table_insert(tbl, strdup("abc"), strdup("123"));
 
     assert_int_equal(pcmk__guint_from_hash(tbl, "abc", 456, &result), pcmk_rc_ok);
     assert_int_equal(result, 123);
 
     g_hash_table_destroy(tbl);
 }
 
 static void
 conversion_errors(void **state)
 {
     GHashTable *tbl = pcmk__strkey_table(free, free);
     guint result;
 
     g_hash_table_insert(tbl, strdup("negative"), strdup("-3"));
     g_hash_table_insert(tbl, strdup("toobig"), strdup("20000000000000000"));
+    g_hash_table_insert(tbl, strdup("baddata"), strdup("asdf"));
 
     assert_int_equal(pcmk__guint_from_hash(tbl, "negative", 456, &result), ERANGE);
     assert_int_equal(result, 456);
 
     assert_int_equal(pcmk__guint_from_hash(tbl, "toobig", 456, &result), ERANGE);
     assert_int_equal(result, 456);
 
+    assert_int_equal(pcmk__guint_from_hash(tbl, "baddata", 456, &result), EINVAL);
+    assert_int_equal(result, 456);
+
     g_hash_table_destroy(tbl);
 }
 
 PCMK__UNIT_TEST(NULL, NULL,
                 cmocka_unit_test(null_args),
                 cmocka_unit_test(missing_key),
                 cmocka_unit_test(standard_usage),
                 cmocka_unit_test(conversion_errors))