diff --git a/src/passport-saml/saml.ts b/src/passport-saml/saml.ts
index 93afc66b..988ec80a 100644
--- a/src/passport-saml/saml.ts
+++ b/src/passport-saml/saml.ts
@@ -198,6 +198,8 @@ class SAML {
       options.RACComparison = "exact";
     }
 
+    options.authnRequestBinding = options.authnRequestBinding || "HTTP-Redirect";
+
     return options as SAMLOptions;
   }
 
diff --git a/src/passport-saml/strategy.ts b/src/passport-saml/strategy.ts
index 93793870..8e42287b 100644
--- a/src/passport-saml/strategy.ts
+++ b/src/passport-saml/strategy.ts
@@ -16,7 +16,6 @@ class Strategy extends PassportStrategy {
   _verify: VerifyWithRequest | VerifyWithoutRequest;
   _saml: saml.SAML;
   _passReqToCallback?: boolean;
-  _authnRequestBinding?: string;
 
   constructor(options: SamlConfig, verify: VerifyWithRequest | VerifyWithoutRequest) {
     super();
@@ -40,7 +39,6 @@ class Strategy extends PassportStrategy {
     this._verify = verify;
     this._saml = new saml.SAML(options);
     this._passReqToCallback = !!options.passReqToCallback;
-    this._authnRequestBinding = options.authnRequestBinding || "HTTP-Redirect";
   }
 
   authenticate(req: RequestWithUser, options: AuthenticateOptions & AuthorizeOptions): void {
@@ -101,7 +99,7 @@ class Strategy extends PassportStrategy {
     } else {
       const requestHandler = {
         "login-request": () => {
-          if (this._authnRequestBinding === "HTTP-POST") {
+          if (this._saml.options.authnRequestBinding === "HTTP-POST") {
             this._saml.getAuthorizeForm(req, (err: Error | null, data?: any) => {
               if (err) {
                 this.error(err);
diff --git a/src/passport-saml/types.ts b/src/passport-saml/types.ts
index 854d3ed3..f9e0ceb0 100644
--- a/src/passport-saml/types.ts
+++ b/src/passport-saml/types.ts
@@ -39,6 +39,7 @@ export interface SAMLOptions {
   authnContext: string | string[];
   forceAuthn: boolean;
   skipRequestCompression: boolean;
+  authnRequestBinding?: string;
   RACComparison: "exact" | "minimum" | "maximum" | "better";
   providerName: string;
   passive: boolean;
@@ -67,7 +68,6 @@ export type SamlConfig = Partial<SAMLOptions> & StrategyOptions;
 interface StrategyOptions {
   name?: string;
   passReqToCallback?: boolean;
-  authnRequestBinding?: string;
 }
 
 export interface SamlScopingConfig {
diff --git a/test/multiSamlStrategy.js b/test/multiSamlStrategy.js
index eb5896b1..b1e7a235 100644
--- a/test/multiSamlStrategy.js
+++ b/test/multiSamlStrategy.js
@@ -2,12 +2,13 @@
 
 var sinon = require("sinon");
 var should = require("should");
+var saml = require("../lib/passport-saml/saml.js");
 var SamlStrategy = require("../lib/passport-saml/index.js").Strategy;
-var MultiSamlStrategy = require("../lib/passport-saml/multiSamlStrategy");
+var MultiSamlStrategy = require("../lib/passport-saml/multiSamlStrategy.js");
 
 function verify() {}
 
-describe("Strategy()", function () {
+describe("MultiSamlStrategy()", function () {
   it("extends passport Strategy", function () {
     function getSamlOptions() {
       return {};
@@ -24,7 +25,7 @@ describe("Strategy()", function () {
   });
 });
 
-describe("strategy#authenticate", function () {
+describe("MultiSamlStrategy#authenticate", function () {
   beforeEach(function () {
     this.superAuthenticateStub = sinon.stub(SamlStrategy.prototype, "authenticate");
   });
@@ -57,12 +58,10 @@ describe("strategy#authenticate", function () {
   it("passes options on to saml strategy", function (done) {
     var passportOptions = {
       passReqToCallback: true,
-      authnRequestBinding: "HTTP-POST",
       getSamlOptions: function (req, fn) {
         try {
           fn();
           strategy._passReqToCallback.should.eql(true);
-          strategy._authnRequestBinding.should.eql("HTTP-POST");
           done();
         } catch (err2) {
           done(err2);
@@ -78,6 +77,7 @@ describe("strategy#authenticate", function () {
     var superAuthenticateStub = this.superAuthenticateStub;
     var samlOptions = {
       issuer: "http://foo.issuer",
+      authnRequestBinding: "HTTP-POST",
       callbackUrl: "http://foo.callback",
       cert: "deadbeef",
       host: "lvh",
@@ -109,7 +109,37 @@ describe("strategy#authenticate", function () {
   });
 });
 
-describe("strategy#logout", function () {
+describe("MultiSamlStrategy#authorize", function () {
+  beforeEach(function () {
+    this.getAuthorizeFormStub = sinon.stub(saml.SAML.prototype, "getAuthorizeForm");
+    this.getAuthorizeUrlStub = sinon.stub(saml.SAML.prototype, "getAuthorizeUrl");
+  });
+
+  afterEach(function () {
+    this.getAuthorizeFormStub.restore();
+    this.getAuthorizeUrlStub.restore();
+  });
+
+  it("calls getAuthorizeForm when authnRequestBinding is HTTP-POST", function () {
+    function getSamlOptions(req, fn) {
+      fn(null, { authnRequestBinding: "HTTP-POST" });
+    }
+    var strategy = new MultiSamlStrategy({ getSamlOptions }, verify);
+    strategy.authenticate({}, {});
+    sinon.assert.calledOnce(this.getAuthorizeFormStub);
+  });
+
+  it("calls getAuthorizeUrl when authnRequestBinding is not HTTP-POST", function () {
+    function getSamlOptions(req, fn) {
+      fn(null, {});
+    }
+    var strategy = new MultiSamlStrategy({ getSamlOptions }, verify);
+    strategy.authenticate({}, {});
+    sinon.assert.calledOnce(this.getAuthorizeUrlStub);
+  });
+});
+
+describe("MultiSamlStrategy#logout", function () {
   beforeEach(function () {
     this.superLogoutMock = sinon.stub(SamlStrategy.prototype, "logout");
   });
@@ -137,12 +167,10 @@ describe("strategy#logout", function () {
   it("passes options on to saml strategy", function (done) {
     var passportOptions = {
       passReqToCallback: true,
-      authnRequestBinding: "HTTP-POST",
       getSamlOptions: function (req, fn) {
         try {
           fn();
           strategy._passReqToCallback.should.eql(true);
-          strategy._authnRequestBinding.should.eql("HTTP-POST");
           done();
         } catch (err2) {
           done(err2);
@@ -159,6 +187,7 @@ describe("strategy#logout", function () {
     var samlOptions = {
       issuer: "http://foo.issuer",
       callbackUrl: "http://foo.callback",
+      authnRequestBinding: "HTTP-POST",
       cert: "deadbeef",
       host: "lvh",
       acceptedClockSkewMs: -1,
@@ -184,7 +213,7 @@ describe("strategy#logout", function () {
   });
 });
 
-describe("strategy#generateServiceProviderMetadata", function () {
+describe("MultiSamlStrategy#generateServiceProviderMetadata", function () {
   beforeEach(function () {
     this.superGenerateServiceProviderMetadata = sinon
       .stub(SamlStrategy.prototype, "generateServiceProviderMetadata")
@@ -216,12 +245,10 @@ describe("strategy#generateServiceProviderMetadata", function () {
   it("passes options on to saml strategy", function (done) {
     var passportOptions = {
       passReqToCallback: true,
-      authnRequestBinding: "HTTP-POST",
       getSamlOptions: function (req, fn) {
         try {
           fn();
           strategy._passReqToCallback.should.eql(true);
-          strategy._authnRequestBinding.should.eql("HTTP-POST");
           done();
         } catch (err2) {
           done(err2);
diff --git a/test/strategy.js b/test/strategy.js
new file mode 100644
index 00000000..06f9c4eb
--- /dev/null
+++ b/test/strategy.js
@@ -0,0 +1,36 @@
+"use strict";
+
+var sinon = require("sinon");
+var saml = require("../lib/passport-saml/saml.js");
+var SamlStrategy = require("../lib/passport-saml/index.js").Strategy;
+
+function verify() {}
+
+describe("strategy#authorize", function () {
+  beforeEach(function () {
+    this.getAuthorizeFormStub = sinon.stub(saml.SAML.prototype, "getAuthorizeForm");
+    this.getAuthorizeUrlStub = sinon.stub(saml.SAML.prototype, "getAuthorizeUrl");
+  });
+
+  afterEach(function () {
+    this.getAuthorizeFormStub.restore();
+    this.getAuthorizeUrlStub.restore();
+  });
+
+  it("calls getAuthorizeForm when authnRequestBinding is HTTP-POST", function () {
+    var strategy = new SamlStrategy(
+      {
+        authnRequestBinding: "HTTP-POST",
+      },
+      verify
+    );
+    strategy.authenticate({}, {});
+    sinon.assert.calledOnce(this.getAuthorizeFormStub);
+  });
+
+  it("calls getAuthorizeUrl when authnRequestBinding is not HTTP-POST", function () {
+    var strategy = new SamlStrategy({}, verify);
+    strategy.authenticate({}, {});
+    sinon.assert.calledOnce(this.getAuthorizeUrlStub);
+  });
+});