diff --git a/lib/common/tests/strings/Makefile.am b/lib/common/tests/strings/Makefile.am
index 9abb8e9a18..01b69fa57c 100644
--- a/lib/common/tests/strings/Makefile.am
+++ b/lib/common/tests/strings/Makefile.am
@@ -1,41 +1,42 @@
 #
-# Copyright 2020-2022 the Pacemaker project contributors
+# Copyright 2020-2023 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 $(top_srcdir)/mk/tap.mk
 include $(top_srcdir)/mk/unittest.mk
 
 # Add "_test" to the end of all test program names to simplify .gitignore.
 check_PROGRAMS = \
 		crm_get_msec_test 	\
 		crm_is_true_test 	\
 		crm_str_to_boolean_test 	\
 		pcmk__add_word_test		\
 		pcmk__btoa_test			\
 		pcmk__char_in_any_str_test	\
 		pcmk__compress_test	\
 		pcmk__ends_with_test 		\
 		pcmk__g_strcat_test		\
 		pcmk__guint_from_hash_test	\
 		pcmk__numeric_strcasecmp_test \
 		pcmk__parse_ll_range_test	\
 		pcmk__s_test				\
 		pcmk__scan_double_test		\
+		pcmk__scan_ll_test			\
 		pcmk__scan_min_int_test		\
 		pcmk__scan_port_test		\
 		pcmk__starts_with_test 		\
 		pcmk__str_any_of_test		\
 		pcmk__str_in_list_test		\
 		pcmk__str_table_dup_test	\
 		pcmk__str_update_test		\
 		pcmk__strcmp_test 			\
 		pcmk__strkey_table_test 	\
 		pcmk__strikey_table_test 	\
 		pcmk__trim_test
 
 TESTS = $(check_PROGRAMS)
diff --git a/lib/common/tests/strings/pcmk__scan_ll_test.c b/lib/common/tests/strings/pcmk__scan_ll_test.c
new file mode 100644
index 0000000000..645ecb4f62
--- /dev/null
+++ b/lib/common/tests/strings/pcmk__scan_ll_test.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2023 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>
+
+static void
+empty_input_string(void **state)
+{
+    long long result;
+
+    assert_int_equal(pcmk__scan_ll(NULL, &result, 47), pcmk_rc_ok);
+    assert_int_equal(result, 47);
+}
+
+static void
+bad_input_string(void **state)
+{
+    long long result;
+
+    assert_int_equal(pcmk__scan_ll("asdf", &result, 47), EINVAL);
+    assert_int_equal(result, 47);
+    assert_int_equal(pcmk__scan_ll("as12", &result, 47), EINVAL);
+    assert_int_equal(result, 47);
+}
+
+static void
+trailing_chars(void **state)
+{
+    long long result;
+
+    assert_int_equal(pcmk__scan_ll("12as", &result, 47), pcmk_rc_ok);
+    assert_int_equal(result, 12);
+}
+
+static void
+no_result_variable(void **state)
+{
+    assert_int_equal(pcmk__scan_ll("1234", NULL, 47), pcmk_rc_ok);
+    assert_int_equal(pcmk__scan_ll("asdf", NULL, 47), EINVAL);
+}
+
+static void
+typical_case(void **state)
+{
+    long long result;
+
+    assert_int_equal(pcmk__scan_ll("1234", &result, 47), pcmk_rc_ok);
+    assert_int_equal(result, 1234);
+}
+
+PCMK__UNIT_TEST(NULL, NULL,
+                cmocka_unit_test(empty_input_string),
+                cmocka_unit_test(bad_input_string),
+                cmocka_unit_test(trailing_chars),
+                cmocka_unit_test(no_result_variable),
+                cmocka_unit_test(typical_case))