diff --git a/src/time.ts b/src/time.ts
index 17b6a0eb..2a35b38a 100644
--- a/src/time.ts
+++ b/src/time.ts
@@ -774,10 +774,10 @@ export class CronTime {
 				let upper = mUpper !== undefined ? parseInt(mUpper, 10) : undefined;
 
 				const wasStepDefined = mStep !== undefined;
-				if (mStep === '0') {
+				const step = parseInt(mStep ?? '1', 10);
+				if (step === 0) {
 					throw new Error(`Field (${unit}) has a step of zero`);
 				}
-				const step = parseInt(mStep ?? '1', 10);
 
 				if (upper !== undefined && lower > upper) {
 					throw new Error(`Field (${unit}) has an invalid range`);
diff --git a/tests/crontime.test.ts b/tests/crontime.test.ts
index 5954a215..3827268b 100644
--- a/tests/crontime.test.ts
+++ b/tests/crontime.test.ts
@@ -210,9 +210,17 @@ describe('crontime', () => {
 	});
 
 	it('should test invalid step', () => {
+		expect(() => {
+			new CronTime('* * * 1/ *');
+		}).toThrow();
+
 		expect(() => {
 			new CronTime('* * * 1/0 *');
 		}).toThrow();
+
+		expect(() => {
+			new CronTime('* * * 1/00 *');
+		}).toThrow();
 	});
 
 	it('should test invalid range', () => {