diff --git a/test/claim-nbf.test.js b/test/claim-nbf.test.js
index 72397de1..d4957241 100644
--- a/test/claim-nbf.test.js
+++ b/test/claim-nbf.test.js
@@ -273,6 +273,32 @@ describe('not before', function() {
       });
     });
 
+    it('should accept a fractional "nbf" that is already active within the current second', function (done) {
+      signWithNotBefore(undefined, {nbf: 60.111}, (e1, token) => {
+        fakeClock.tick(999);
+        testUtils.verifyJWTHelper(token, 'secret', {}, (e2, decoded) => {
+          testUtils.asyncCheck(done, () => {
+            expect(e1).to.be.null;
+            expect(e2).to.be.null;
+            expect(decoded).to.have.property('nbf', 60.111);
+          });
+        })
+      });
+    });
+
+    it('should error on verify if a fractional "nbf" is after current time within the same second', function (done) {
+      signWithNotBefore(undefined, {nbf: 60.5}, (e1, token) => {
+        fakeClock.tick(200);
+        testUtils.verifyJWTHelper(token, 'secret', {}, (e2) => {
+          testUtils.asyncCheck(done, () => {
+            expect(e1).to.be.null;
+            expect(e2).to.be.instanceOf(jwt.NotBeforeError);
+            expect(e2).to.have.property('message', 'jwt not active');
+          });
+        })
+      });
+    });
+
     it('should verify "nbf" using "clockTimestamp"', function (done) {
       signWithNotBefore(10, {}, (e1, token) => {
         testUtils.verifyJWTHelper(token, 'secret', {clockTimestamp: 70}, (e2, decoded) => {
diff --git a/verify.js b/verify.js
index cdbfdc45..3d7417bc 100644
--- a/verify.js
+++ b/verify.js
@@ -54,7 +54,9 @@ module.exports = function (jwtString, secretOrPublicKey, options, callback) {
     return done(new JsonWebTokenError('allowInvalidAsymmetricKeyTypes must be a boolean'));
   }
 
-  const clockTimestamp = options.clockTimestamp || Math.floor(Date.now() / 1000);
+  const now = Date.now() / 1000;
+  const clockTimestamp = options.clockTimestamp || Math.floor(now);
+  const notBeforeTimestamp = options.clockTimestamp || now;
 
   if (!jwtString){
     return done(new JsonWebTokenError('jwt must be provided'));
@@ -177,7 +179,7 @@ module.exports = function (jwtString, secretOrPublicKey, options, callback) {
       if (typeof payload.nbf !== 'number') {
         return done(new JsonWebTokenError('invalid nbf value'));
       }
-      if (payload.nbf > clockTimestamp + (options.clockTolerance || 0)) {
+      if (payload.nbf > notBeforeTimestamp + (options.clockTolerance || 0)) {
         return done(new NotBeforeError('jwt not active', new Date(payload.nbf * 1000)));
       }
     }