diff --git a/lib/middleware/initialize.js b/lib/middleware/initialize.js
index 90b869b6..47ba7e86 100644
--- a/lib/middleware/initialize.js
+++ b/lib/middleware/initialize.js
@@ -52,7 +52,40 @@ module.exports = function initialize(passport, options) {
     if (options.userProperty) {
       req._userProperty = options.userProperty;
     }
-
+    
+    var compat = (options.compat === undefined) ? true : options.compat;
+    if (compat) {
+      // `passport@0.5.1` [removed][1] all internal use of `req._passport`.
+      // From the standpoint of this package, this should have been a
+      // non-breaking change.  However, some strategies (such as `passport-azure-ad`)
+      // depend directly on `passport@0.4.x` or earlier.  `require`-ing earlier
+      // versions of `passport` has the effect of monkeypatching `http.IncomingMessage`
+      // with `logIn`, `logOut`, `isAuthenticated` and `isUnauthenticated`
+      // functions that [expect][2] the `req._passport` property to exist.
+      // Since pre-existing functions on `req` are given [preference][3], this
+      // results in [issues][4].
+      //
+      // The changes here restore the expected properties needed when earlier
+      // versions of `passport` are `require`-ed.  This compatibility mode is
+      // enabled by default, and can be disabld by simply not `use`-ing `passport.initialize()`
+      // middleware or setting `compat: false` as an option to the middleware.
+      //
+      // An alternative approach to addressing this issue would be to not
+      // preferentially use pre-existing functions on `req`, but rather always
+      // overwrite `req.logIn`, etc. with the versions of those functions shiped
+      // with `authenticate()` middleware.  This option should be reconsidered
+      // in a future major version release.
+      //
+      // [1]: https://github.com/jaredhanson/passport/pull/875
+      // [2]: https://github.com/jaredhanson/passport/blob/v0.4.1/lib/http/request.js
+      // [3]: https://github.com/jaredhanson/passport/blob/v0.5.1/lib/middleware/authenticate.js#L96
+      // [4]: https://github.com/jaredhanson/passport/issues/877
+      passport._userProperty = options.userProperty || 'user';
+      
+      req._passport = {};
+      req._passport.instance = passport;
+    }
+    
     next();
   };
 };
diff --git a/test/authenticator.middleware.test.js b/test/authenticator.middleware.test.js
index bf6d0074..a6d77ef0 100644
--- a/test/authenticator.middleware.test.js
+++ b/test/authenticator.middleware.test.js
@@ -42,6 +42,14 @@ describe('Authenticator', function() {
       it('should not initialize namespace within session', function() {
         expect(request.session.passport).to.be.undefined;
       });
+      
+      it('should expose authenticator on internal request property', function() {
+        expect(request._passport).to.be.an('object');
+        expect(request._passport.instance).to.be.an.instanceOf(Authenticator);
+        expect(request._passport.instance).to.equal(passport);
+        expect(request._passport.instance._sm).to.be.an('object');
+        expect(request._passport.instance._userProperty).to.equal('user');
+      });
     });
     
     describe('handling a request with custom user property', function() {
@@ -72,6 +80,14 @@ describe('Authenticator', function() {
       it('should not initialize namespace within session', function() {
         expect(request.session.passport).to.be.undefined;
       });
+      
+      it('should expose authenticator on internal request property', function() {
+        expect(request._passport).to.be.an('object');
+        expect(request._passport.instance).to.be.an.instanceOf(Authenticator);
+        expect(request._passport.instance).to.equal(passport);
+        expect(request._passport.instance._sm).to.be.an('object');
+        expect(request._passport.instance._userProperty).to.equal('currentUser');
+      });
     });
     
   });
diff --git a/test/middleware/initialize.test.js b/test/middleware/initialize.test.js
index acef7a38..b572f93b 100644
--- a/test/middleware/initialize.test.js
+++ b/test/middleware/initialize.test.js
@@ -31,6 +31,14 @@ describe('middleware/initialize', function() {
     it('should not error', function() {
       expect(error).to.be.undefined;
     });
+    
+    it('should expose authenticator on internal request property', function() {
+      expect(request._passport).to.be.an('object');
+      expect(request._passport.instance).to.be.an.instanceOf(Passport);
+      expect(request._passport.instance).to.equal(passport);
+      expect(request._passport.instance._sm).to.be.an('object');
+      expect(request._passport.instance._userProperty).to.equal('user');
+    });
   });
   
   describe('handling a request with a new session', function() {
@@ -58,6 +66,14 @@ describe('middleware/initialize', function() {
     it('should not initialize namespace within session', function() {
       expect(request.session.passport).to.be.undefined;
     });
+    
+    it('should expose authenticator on internal request property', function() {
+      expect(request._passport).to.be.an('object');
+      expect(request._passport.instance).to.be.an.instanceOf(Passport);
+      expect(request._passport.instance).to.equal(passport);
+      expect(request._passport.instance._sm).to.be.an('object');
+      expect(request._passport.instance._userProperty).to.equal('user');
+    });
   });
   
   describe('handling a request with an existing session', function() {
@@ -89,6 +105,14 @@ describe('middleware/initialize', function() {
       expect(Object.keys(request.session.passport)).to.have.length(1);
       expect(request.session.passport.user).to.equal('123456');
     });
+    
+    it('should expose authenticator on internal request property', function() {
+      expect(request._passport).to.be.an('object');
+      expect(request._passport.instance).to.be.an.instanceOf(Passport);
+      expect(request._passport.instance).to.equal(passport);
+      expect(request._passport.instance._sm).to.be.an('object');
+      expect(request._passport.instance._userProperty).to.equal('user');
+    });
   });
   
   describe('handling a request with an existing session using custom session key', function() {
@@ -121,6 +145,45 @@ describe('middleware/initialize', function() {
       expect(Object.keys(request.session.authentication)).to.have.length(1);
       expect(request.session.authentication.user).to.equal('123456');
     });
+    
+    it('should expose authenticator on internal request property', function() {
+      expect(request._passport).to.be.an('object');
+      expect(request._passport.instance).to.be.an.instanceOf(Passport);
+      expect(request._passport.instance).to.equal(passport);
+      expect(request._passport.instance._sm).to.be.an('object');
+      expect(request._passport.instance._userProperty).to.equal('user');
+    });
+  });
+  
+  describe('handling a request with a new session without compat mode', function() {
+    var passport = new Passport();
+    var request, error;
+
+    before(function(done) {
+      chai.connect.use(initialize(passport, { compat: false }))
+        .req(function(req) {
+          request = req;
+          
+          req.session = {};
+        })
+        .next(function(err) {
+          error = err;
+          done();
+        })
+        .dispatch();
+    });
+    
+    it('should not error', function() {
+      expect(error).to.be.undefined;
+    });
+    
+    it('should not initialize namespace within session', function() {
+      expect(request.session.passport).to.be.undefined;
+    });
+    
+    it('should expose authenticator on internal request property', function() {
+      expect(request._passport).to.be.undefined;
+    });
   });
   
 });