diff --git a/lib/strategy.js b/lib/strategy.js
index 0902ec5..07b87f1 100644
--- a/lib/strategy.js
+++ b/lib/strategy.js
@@ -252,7 +252,7 @@ OAuth2Strategy.prototype.authenticate = function(req, options) {
     }
 
     var state = options.state;
-    if (state && typeof state !== 'object') {
+    if (state && typeof state == 'string') {
       // NOTE: In passport-oauth2@1.5.0 and earlier, `state` could be passed as
       //       an object.  However, it would result in an empty string being
       //       serialized as the value of the query parameter by `url.format()`,
diff --git a/test/oauth2.pkce.test.js b/test/oauth2.pkce.test.js
index 2b13b15..90a5f47 100644
--- a/test/oauth2.pkce.test.js
+++ b/test/oauth2.pkce.test.js
@@ -127,6 +127,74 @@ describe('OAuth2Strategy', function() {
       });
     });
     
+    describe('handling a request to be redirected for authorization with state set to boolean true', function() {
+      var request, url;
+
+      before(function(done) {
+        chai.passport.use(strategy)
+          .redirect(function(u) {
+            url = u;
+            done();
+          })
+          .req(function(req) {
+            request = req;
+            req.session = {};
+          })
+          .authenticate({ state: true });
+      });
+
+      it('should be redirected', function() {
+        var u = uri.parse(url, true);
+        expect(u.query.state).to.have.length(24);
+        expect(u.query.code_challenge).to.have.length(43);
+        expect(u.query.code_challenge).to.equal('E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM')
+        expect(u.query.code_challenge_method).to.equal('S256');
+      });
+    
+      it('should save verifier in session', function() {
+        var u = uri.parse(url, true);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.have.length(24);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.equal(u.query.state);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.have.length(43);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.equal('dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk');
+        expect(request.session['oauth2:www.example.com'].state.state).to.equal(true);
+      });
+    });
+    
+    describe('handling a request to be redirected for authorization with state set to boolean false', function() {
+      var request, url;
+
+      before(function(done) {
+        chai.passport.use(strategy)
+          .redirect(function(u) {
+            url = u;
+            done();
+          })
+          .req(function(req) {
+            request = req;
+            req.session = {};
+          })
+          .authenticate({ state: false });
+      });
+
+      it('should be redirected', function() {
+        var u = uri.parse(url, true);
+        expect(u.query.state).to.have.length(24);
+        expect(u.query.code_challenge).to.have.length(43);
+        expect(u.query.code_challenge).to.equal('E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM')
+        expect(u.query.code_challenge_method).to.equal('S256');
+      });
+    
+      it('should save verifier in session', function() {
+        var u = uri.parse(url, true);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.have.length(24);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.equal(u.query.state);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.have.length(43);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.equal('dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk');
+        expect(request.session['oauth2:www.example.com'].state.state).to.be.undefined;
+      });
+    });
+    
     describe('that redirects to service provider with other data in session', function() {
       var request, url;
 
diff --git a/test/oauth2.store.pkce.test.js b/test/oauth2.store.pkce.test.js
index 8ca1d00..8fb6bf4 100644
--- a/test/oauth2.store.pkce.test.js
+++ b/test/oauth2.store.pkce.test.js
@@ -112,6 +112,74 @@ describe('OAuth2Strategy', function() {
       });
     });
     
+    describe('handling a request to be redirected for authorization with state as boolean true', function() {
+      var request, url;
+
+      before(function(done) {
+        chai.passport.use(strategy)
+          .redirect(function(u) {
+            url = u;
+            done();
+          })
+          .req(function(req) {
+            request = req;
+            req.session = {};
+          })
+          .authenticate({ state: true });
+      });
+
+      it('should be redirected', function() {
+        var u = uri.parse(url, true);
+        expect(u.query.state).to.have.length(24);
+        expect(u.query.code_challenge).to.have.length(43);
+        expect(u.query.code_challenge).to.equal('E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM')
+        expect(u.query.code_challenge_method).to.equal('S256');
+      });
+    
+      it('should save verifier in session', function() {
+        var u = uri.parse(url, true);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.have.length(24);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.equal(u.query.state);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.have.length(43);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.equal('dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk');
+        expect(request.session['oauth2:www.example.com'].state.state).to.equal(true);
+      });
+    });
+    
+    describe('handling a request to be redirected for authorization with state as boolean false', function() {
+      var request, url;
+
+      before(function(done) {
+        chai.passport.use(strategy)
+          .redirect(function(u) {
+            url = u;
+            done();
+          })
+          .req(function(req) {
+            request = req;
+            req.session = {};
+          })
+          .authenticate({ state: false });
+      });
+
+      it('should be redirected', function() {
+        var u = uri.parse(url, true);
+        expect(u.query.state).to.have.length(24);
+        expect(u.query.code_challenge).to.have.length(43);
+        expect(u.query.code_challenge).to.equal('E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM')
+        expect(u.query.code_challenge_method).to.equal('S256');
+      });
+    
+      it('should save verifier in session', function() {
+        var u = uri.parse(url, true);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.have.length(24);
+        expect(request.session['oauth2:www.example.com'].state.handle).to.equal(u.query.state);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.have.length(43);
+        expect(request.session['oauth2:www.example.com'].state.code_verifier).to.equal('dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk');
+        expect(request.session['oauth2:www.example.com'].state.state).to.be.undefined;
+      });
+    });
+    
     describe('that redirects to service provider with other data in session', function() {
       var request, url;
 
diff --git a/test/oauth2.store.test.js b/test/oauth2.store.test.js
index a63a0e9..c23743e 100644
--- a/test/oauth2.store.test.js
+++ b/test/oauth2.store.test.js
@@ -83,6 +83,66 @@ describe('OAuth2Strategy', function() {
         });
       }); // that redirects to service provider with state
       
+      describe('that redirects to service provider with state set to boolean true', function() {
+        var request, url;
+  
+        before(function(done) {
+          chai.passport.use(strategy)
+            .redirect(function(u) {
+              url = u;
+              done();
+            })
+            .req(function(req) {
+              request = req;
+              req.session = {};
+            })
+            .authenticate({ state: true });
+        });
+  
+        it('should be redirected', function() {
+          var u = uri.parse(url, true);
+          expect(u.query.state).to.have.length(24);
+        });
+      
+        it('should save state in session', function() {
+          var u = uri.parse(url, true);
+          
+          expect(request.session['oauth2:www.example.com'].state.handle).to.have.length(24);
+          expect(request.session['oauth2:www.example.com'].state.handle).to.equal(u.query.state);
+          expect(request.session['oauth2:www.example.com'].state.state).to.equal(true);
+        });
+      }); // that redirects to service provider with state set to boolean true
+      
+      describe('that redirects to service provider with state set to boolean false', function() {
+        var request, url;
+  
+        before(function(done) {
+          chai.passport.use(strategy)
+            .redirect(function(u) {
+              url = u;
+              done();
+            })
+            .req(function(req) {
+              request = req;
+              req.session = {};
+            })
+            .authenticate({ state: false });
+        });
+  
+        it('should be redirected', function() {
+          var u = uri.parse(url, true);
+          expect(u.query.state).to.have.length(24);
+        });
+      
+        it('should save state in session', function() {
+          var u = uri.parse(url, true);
+          
+          expect(request.session['oauth2:www.example.com'].state.handle).to.have.length(24);
+          expect(request.session['oauth2:www.example.com'].state.handle).to.equal(u.query.state);
+          expect(request.session['oauth2:www.example.com'].state.state).to.be.undefined;
+        });
+      }); // that redirects to service provider with state set to boolean false
+      
       describe('that redirects to service provider with other data in session', function() {
         var request, url;