diff --git a/src/shared/calendarspec.c b/src/shared/calendarspec.c
index 51ade0e887..273a38f1fa 100644
--- a/src/shared/calendarspec.c
+++ b/src/shared/calendarspec.c
@@ -298,7 +298,7 @@ static void format_chain(FILE *f, int space, const CalendarComponent *c, bool us
                 return;
         }
 
-        if (usec && c->start == 0 && c->repeat == USEC_PER_SEC && !c->next) {
+        if (usec && c->start == 0 && c->stop < 0 && c->repeat == USEC_PER_SEC && !c->next) {
                 fputc('*', f);
                 return;
         }
diff --git a/src/test/test-calendarspec.c b/src/test/test-calendarspec.c
index cf6965dd3c..5508f8b833 100644
--- a/src/test/test-calendarspec.c
+++ b/src/test/test-calendarspec.c
@@ -162,6 +162,8 @@ TEST(calendar_spec_one) {
         test_one("00:00:1.0..3.8", "*-*-* 00:00:01..03");
         test_one("00:00:01..03", "*-*-* 00:00:01..03");
         test_one("00:00:01/2,02..03", "*-*-* 00:00:01/2,02..03");
+        test_one("*:4,30:0..3", "*-*-* *:04,30:00..03");
+        test_one("*:4,30:0/1", "*-*-* *:04,30:*");
         test_one("*-*~1 Utc", "*-*~01 00:00:00 UTC");
         test_one("*-*~05,3 ", "*-*~03,05 00:00:00");
         test_one("*-*~* 00:00:00", "*-*-* 00:00:00");
@@ -252,6 +254,9 @@ TEST(calendar_spec_from_string) {
         assert_se(calendar_spec_from_string("00:00:2300", &c) == -ERANGE);
         assert_se(calendar_spec_from_string("00:00:18446744073709551615", &c) == -ERANGE);
         assert_se(calendar_spec_from_string("@88588582097858858", &c) == -ERANGE);
+        assert_se(calendar_spec_from_string("*:4,30:*,5", &c) == -EINVAL);
+        assert_se(calendar_spec_from_string("*:4,30:5,*", &c) == -EINVAL);
+        assert_se(calendar_spec_from_string("*:4,30:*\n", &c) == -EINVAL);
 }
 
 DEFINE_TEST_MAIN(LOG_INFO);
diff --git a/test/fuzz/fuzz-calendarspec/cant-parse-printed b/test/fuzz/fuzz-calendarspec/cant-parse-printed
new file mode 100644
index 0000000000..e2c82a620e
--- /dev/null
+++ b/test/fuzz/fuzz-calendarspec/cant-parse-printed
@@ -0,0 +1 @@
+*:4,30:0..5,0
\ No newline at end of file
diff --git a/test/fuzz/fuzz-calendarspec/print-loses-spec b/test/fuzz/fuzz-calendarspec/print-loses-spec
new file mode 100644
index 0000000000..5e36de2e87
--- /dev/null
+++ b/test/fuzz/fuzz-calendarspec/print-loses-spec
@@ -0,0 +1 @@
+*:4,30:0..3
\ No newline at end of file