diff --git a/vlib/time/custom_format_test.v b/vlib/time/custom_format_test.v
index 79290fe084..0e706c18ce 100644
--- a/vlib/time/custom_format_test.v
+++ b/vlib/time/custom_format_test.v
@@ -9,3 +9,57 @@ fn test_custom_format() {
 
 	println(date.custom_format(test_str))
 }
+
+fn test_hh() {
+	assert time.parse('2023-08-04 00:00:45')!.custom_format('hh') == '00'
+	assert time.parse('2023-08-04 01:00:45')!.custom_format('hh') == '01'
+	assert time.parse('2023-08-04 02:00:45')!.custom_format('hh') == '02'
+	assert time.parse('2023-08-04 03:00:45')!.custom_format('hh') == '03'
+	assert time.parse('2023-08-04 04:00:45')!.custom_format('hh') == '04'
+	assert time.parse('2023-08-04 05:00:45')!.custom_format('hh') == '05'
+	assert time.parse('2023-08-04 06:00:45')!.custom_format('hh') == '06'
+	assert time.parse('2023-08-04 07:00:45')!.custom_format('hh') == '07'
+	assert time.parse('2023-08-04 08:00:45')!.custom_format('hh') == '08'
+	assert time.parse('2023-08-04 09:00:45')!.custom_format('hh') == '09'
+	assert time.parse('2023-08-04 10:00:45')!.custom_format('hh') == '10'
+	assert time.parse('2023-08-04 11:00:45')!.custom_format('hh') == '11'
+	assert time.parse('2023-08-04 12:00:45')!.custom_format('hh') == '12'
+	assert time.parse('2023-08-04 13:00:45')!.custom_format('hh') == '01'
+	assert time.parse('2023-08-04 14:00:45')!.custom_format('hh') == '02'
+	assert time.parse('2023-08-04 15:00:45')!.custom_format('hh') == '03'
+	assert time.parse('2023-08-04 16:00:45')!.custom_format('hh') == '04'
+	assert time.parse('2023-08-04 17:00:45')!.custom_format('hh') == '05'
+	assert time.parse('2023-08-04 18:00:45')!.custom_format('hh') == '06'
+	assert time.parse('2023-08-04 19:00:45')!.custom_format('hh') == '07'
+	assert time.parse('2023-08-04 20:00:45')!.custom_format('hh') == '08'
+	assert time.parse('2023-08-04 21:00:45')!.custom_format('hh') == '09'
+	assert time.parse('2023-08-04 22:00:45')!.custom_format('hh') == '10'
+	assert time.parse('2023-08-04 23:00:45')!.custom_format('hh') == '11'
+}
+
+fn test_h() {
+	assert time.parse('2023-08-04 00:00:45')!.custom_format('h') == '0'
+	assert time.parse('2023-08-04 01:00:45')!.custom_format('h') == '1'
+	assert time.parse('2023-08-04 02:00:45')!.custom_format('h') == '2'
+	assert time.parse('2023-08-04 03:00:45')!.custom_format('h') == '3'
+	assert time.parse('2023-08-04 04:00:45')!.custom_format('h') == '4'
+	assert time.parse('2023-08-04 05:00:45')!.custom_format('h') == '5'
+	assert time.parse('2023-08-04 06:00:45')!.custom_format('h') == '6'
+	assert time.parse('2023-08-04 07:00:45')!.custom_format('h') == '7'
+	assert time.parse('2023-08-04 08:00:45')!.custom_format('h') == '8'
+	assert time.parse('2023-08-04 09:00:45')!.custom_format('h') == '9'
+	assert time.parse('2023-08-04 10:00:45')!.custom_format('h') == '10'
+	assert time.parse('2023-08-04 11:00:45')!.custom_format('h') == '11'
+	assert time.parse('2023-08-04 12:00:45')!.custom_format('h') == '12'
+	assert time.parse('2023-08-04 13:00:45')!.custom_format('h') == '1'
+	assert time.parse('2023-08-04 14:00:45')!.custom_format('h') == '2'
+	assert time.parse('2023-08-04 15:00:45')!.custom_format('h') == '3'
+	assert time.parse('2023-08-04 16:00:45')!.custom_format('h') == '4'
+	assert time.parse('2023-08-04 17:00:45')!.custom_format('h') == '5'
+	assert time.parse('2023-08-04 18:00:45')!.custom_format('h') == '6'
+	assert time.parse('2023-08-04 19:00:45')!.custom_format('h') == '7'
+	assert time.parse('2023-08-04 20:00:45')!.custom_format('h') == '8'
+	assert time.parse('2023-08-04 21:00:45')!.custom_format('h') == '9'
+	assert time.parse('2023-08-04 22:00:45')!.custom_format('h') == '10'
+	assert time.parse('2023-08-04 23:00:45')!.custom_format('h') == '11'
+}
diff --git a/vlib/time/format.v b/vlib/time/format.v
index eceb8b6246..6fca0b0fb4 100644
--- a/vlib/time/format.v
+++ b/vlib/time/format.v
@@ -221,10 +221,12 @@ pub fn (t Time) custom_format(s string) string {
 				sb.write_string('${t.hour:02}')
 			}
 			'h' {
-				sb.write_string((t.hour % 12).str())
+				h := if t.hour > 12 { t.hour - 12 } else { t.hour }
+				sb.write_string(h.str())
 			}
 			'hh' {
-				sb.write_string('${(t.hour % 12):02}')
+				h := if t.hour > 12 { t.hour - 12 } else { t.hour }
+				sb.write_string('${h:02}')
 			}
 			'm' {
 				sb.write_string(t.minute.str())