diff --git a/lib/time.js b/lib/time.js
index 3b9e54c8..5c4a98a5 100644
--- a/lib/time.js
+++ b/lib/time.js
@@ -768,7 +768,7 @@ function CronTime(luxon) {
 				if (allRanges[i].match(RE_RANGE)) {
 					allRanges[i].replace(RE_RANGE, ($0, lower, upper, step) => {
 						lower = parseInt(lower, 10);
-						upper = parseInt(upper, 10) || undefined;
+						upper = upper !== undefined ? parseInt(upper, 10) : undefined;
 
 						const wasStepDefined = !isNaN(parseInt(step, 10));
 						if (step === '0') {
@@ -776,14 +776,14 @@ function CronTime(luxon) {
 						}
 						step = parseInt(step, 10) || 1;
 
-						if (upper && lower > upper) {
+						if (upper !== undefined && lower > upper) {
 							throw new Error(`Field (${type}) has an invalid range`);
 						}
 
 						const outOfRangeError =
 							lower < low ||
-							(upper && upper > high) ||
-							(!upper && lower > high);
+							(upper !== undefined && upper > high) ||
+							(upper === undefined && lower > high);
 
 						if (outOfRangeError) {
 							throw new Error(`Field value (${value}) is out of range`);
@@ -793,7 +793,7 @@ function CronTime(luxon) {
 						lower = Math.min(Math.max(low, ~~Math.abs(lower)), high);
 
 						// Positive integer lower than constraints[1]
-						if (upper) {
+						if (upper !== undefined) {
 							upper = Math.min(high, ~~Math.abs(upper));
 						} else {
 							// If step is provided, the default upper range is the highest value
diff --git a/tests/crontime.test.js b/tests/crontime.test.js
index 0d962d06..d6721bd2 100644
--- a/tests/crontime.test.js
+++ b/tests/crontime.test.js
@@ -70,6 +70,12 @@ describe('crontime', () => {
 		}).not.toThrow();
 	});
 
+	it('should accept all valid ranges (0-59 0-59 1-23 1-31 0-12 0-6)', () => {
+		expect(() => {
+			new cron.CronTime('0-59 0-59 1-23 1-31 0-11 0-6');
+		}).not.toThrow();
+	});
+
 	it('should test comma (0,10 * * * * *)', () => {
 		expect(() => {
 			new cron.CronTime('0,10 * * * * *');
@@ -152,6 +158,14 @@ describe('crontime', () => {
 		expect(() => {
 			new cron.CronTime('* 2-1 * * *');
 		}).toThrow();
+
+		expect(() => {
+			new cron.CronTime('* 2-0 * * *');
+		}).toThrow();
+
+		expect(() => {
+			new cron.CronTime('* 2- * * *');
+		}).toThrow();
 	});
 
 	it('should test Date', () => {