diff --git a/lib/deploy/stepFunctions/compileStateMachines.test.js b/lib/deploy/stepFunctions/compileStateMachines.test.js
index 93ffefb7..375e79eb 100644
--- a/lib/deploy/stepFunctions/compileStateMachines.test.js
+++ b/lib/deploy/stepFunctions/compileStateMachines.test.js
@@ -711,4 +711,35 @@ describe('#compileStateMachines', () => {
     expect(params).to.haveOwnProperty(functionParam2);
     expect(params[functionParam2]).to.eql({ Ref: 'MyFunction2' });
   });
+
+  it('should allow null values #193', () => {
+    serverless.service.stepFunctions = {
+      stateMachines: {
+        myStateMachine1: {
+          id: 'Test',
+          name: 'test',
+          definition: {
+            StartAt: 'AnyStep',
+            States: {
+              AnyStep: {
+                Type: 'Pass',
+                ResultPath: null,
+                Next: 'Finish',
+              },
+              Finish: {
+                Type: 'Succeed',
+              },
+            },
+          },
+        },
+      },
+    };
+
+    serverlessStepFunctions.compileStateMachines();
+    const stateMachine = serverlessStepFunctions.serverless.service
+      .provider.compiledCloudFormationTemplate.Resources
+      .Test;
+
+    expect(stateMachine.Properties.DefinitionString).to.not.equal(null);
+  });
 });
diff --git a/lib/utils/aws.js b/lib/utils/aws.js
index 4b3a10ba..0abed9bb 100644
--- a/lib/utils/aws.js
+++ b/lib/utils/aws.js
@@ -1,5 +1,7 @@
+const _ = require('lodash');
+
 function isIntrinsic(obj) {
-  return typeof obj === 'object' &&
+  return _.isObjectLike(obj) &&
     Object.keys(obj).some((k) => k.startsWith('Fn::') || k.startsWith('Ref'));
 }