diff --git a/lib/server.js b/lib/server.js
index 97fe839d1..3fbee3e07 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -323,7 +323,8 @@ Server.prototype.handshake = function (transportName, req) {
       headers['Set-Cookie'] = cookieMod.serialize(self.cookie, id,
         {
           path: self.cookiePath,
-          httpOnly: self.cookiePath ? self.cookieHttpOnly : false
+          httpOnly: self.cookiePath ? self.cookieHttpOnly : false,
+          sameSite: true
         });
     });
   }
diff --git a/test/server.js b/test/server.js
index 9da4d109b..0d49c8a5b 100644
--- a/test/server.js
+++ b/test/server.js
@@ -117,7 +117,7 @@ describe('server', function () {
             expect(err).to.be(null);
             // hack-obtain sid
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/; HttpOnly');
+            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/; HttpOnly; SameSite=Strict');
             done();
           });
       });
@@ -130,7 +130,7 @@ describe('server', function () {
           .end(function (err, res) {
             expect(err).to.be(null);
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('woot=' + sid + '; Path=/; HttpOnly');
+            expect(res.headers['set-cookie'][0]).to.be('woot=' + sid + '; Path=/; HttpOnly; SameSite=Strict');
             done();
           });
       });
@@ -143,7 +143,7 @@ describe('server', function () {
           .end(function (err, res) {
             expect(err).to.be(null);
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/custom; HttpOnly');
+            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/custom; HttpOnly; SameSite=Strict');
             done();
           });
       });
@@ -156,7 +156,7 @@ describe('server', function () {
           .end(function (err, res) {
             expect(err).to.be(null);
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('io=' + sid);
+            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; SameSite=Strict');
             done();
           });
       });
@@ -169,7 +169,7 @@ describe('server', function () {
           .end(function (err, res) {
             expect(err).to.be(null);
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/; HttpOnly');
+            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/; HttpOnly; SameSite=Strict');
             done();
           });
       });
@@ -182,7 +182,7 @@ describe('server', function () {
           .end(function (err, res) {
             expect(err).to.be(null);
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('io=' + sid);
+            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; SameSite=Strict');
             done();
           });
       });
@@ -195,7 +195,7 @@ describe('server', function () {
           .end(function (err, res) {
             expect(err).to.be(null);
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/');
+            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/; SameSite=Strict');
             done();
           });
       });
@@ -208,7 +208,7 @@ describe('server', function () {
           .end(function (err, res) {
             expect(err).to.be(null);
             var sid = res.text.match(/"sid":"([^"]+)"/)[1];
-            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/; HttpOnly');
+            expect(res.headers['set-cookie'][0]).to.be('io=' + sid + '; Path=/; HttpOnly; SameSite=Strict');
             done();
           });
       });