diff --git a/contracts/PeriodicTokenVesting.sol b/contracts/PeriodicTokenVesting.sol
index e0d6457..33425f5 100644
--- a/contracts/PeriodicTokenVesting.sol
+++ b/contracts/PeriodicTokenVesting.sol
@@ -108,6 +108,8 @@ contract PeriodicTokenVesting is OwnableUpgradeable, PausableUpgradeable {
             "PeriodicTokenVesting#initialize: INVALID_TOKEN"
         );
 
+        require(_start != 0, "PeriodicTokenVesting#initialize: INVALID_START");
+
         require(
             _period != 0,
             "PeriodicTokenVesting#initialize: INVALID_PERIOD_DURATION"
diff --git a/test/PeriodicTokenVesting.spec.js b/test/PeriodicTokenVesting.spec.js
index 9c7f583..c114d90 100644
--- a/test/PeriodicTokenVesting.spec.js
+++ b/test/PeriodicTokenVesting.spec.js
@@ -171,6 +171,15 @@ describe("PeriodicTokenVesting", () => {
         "PeriodicTokenVesting#initialize: INVALID_VESTED_PER_PERIOD_LENGTH"
       );
     });
+
+    it("reverts when start is 0", async () => {
+      initParams.start = 0;
+      initParamsList = Object.values(initParams);
+
+      await expect(vesting.initialize(...initParamsList)).to.be.revertedWith(
+        "PeriodicTokenVesting#initialize: INVALID_START"
+      );
+    });
   });
 
   describe("getTotal", () => {