diff --git a/lib/modem.js b/lib/modem.js
index 846d98b..60ec49e 100644
--- a/lib/modem.js
+++ b/lib/modem.js
@@ -90,6 +90,11 @@ var Modem = function (options) {
   this.headers = opts.headers || {};
   this.sshOptions = Object.assign({}, options ? options.sshOptions : {}, optDefaults.sshOptions);
 
+  // Support sshAuthAgent for backwards-compatibility with d2f92b22cf284d537a57cc255ba11b4c4c5d7b61
+  if (options && options.sshAuthAgent) {
+    this.sshOptions.agent = options.sshAuthAgent;
+  }
+
   if (this.key && this.cert && this.ca) {
     this.protocol = 'https';
   }
diff --git a/test/modem_test.js b/test/modem_test.js
index 1de08e2..640eaea 100644
--- a/test/modem_test.js
+++ b/test/modem_test.js
@@ -169,4 +169,14 @@ describe('Modem', function() {
     assert.strictEqual(modem.sshOptions.agent, '/var/lib/sock');
     assert.strictEqual(modem.sshOptions.foo, 'bar');
   });
+
+  it('supports custom sshAuthAgent for backwards-compatibility', function() {
+    process.env.DOCKER_HOST = 'ssh://user@192.168.59.105:5555';
+    process.env.SSH_AUTH_SOCK = '/var/lib/sock';
+
+    var modem = new Modem({
+      sshAuthAgent: '/var/lib/custom_agent',
+    });
+    assert.strictEqual(modem.sshOptions.agent, '/var/lib/custom_agent');
+  });
 });