diff --git a/packages/dynamodb-data-mapper/src/DataMapper.spec.ts b/packages/dynamodb-data-mapper/src/DataMapper.spec.ts
index d525e0e3..e256e185 100644
--- a/packages/dynamodb-data-mapper/src/DataMapper.spec.ts
+++ b/packages/dynamodb-data-mapper/src/DataMapper.spec.ts
@@ -694,7 +694,7 @@ describe('DataMapper', () => {
 
         const mapper = new DataMapper({
             client: mockDynamoDbClient as any,
-        });    
+        });
 
         class Item {
             get [DynamoDbTable]() { return 'foo' }
@@ -1800,7 +1800,7 @@ describe('DataMapper', () => {
         const describeTablePromiseFunc = jest.fn(() => Promise.resolve({
             Table: {
                 TableStatus: 'ACTIVE',
-                GlobalSecondaryIndexes: [ 
+                GlobalSecondaryIndexes: [
                     {
                         IndexName: 'DescriptionIndex'
                     }
@@ -3892,7 +3892,7 @@ describe('DataMapper', () => {
                         };
                     }
                 },
-                {startKey: {fizz: 100}}
+                {startKey: {fizz: 100, pop: 20}}
             );
 
             await results.next();
diff --git a/packages/dynamodb-data-mapper/src/marshallStartKey.ts b/packages/dynamodb-data-mapper/src/marshallStartKey.ts
index f34931dd..b1bcda0d 100644
--- a/packages/dynamodb-data-mapper/src/marshallStartKey.ts
+++ b/packages/dynamodb-data-mapper/src/marshallStartKey.ts
@@ -11,8 +11,8 @@ export function marshallStartKey(
     const key: Key = {};
     for (const propertyName of Object.keys(startKey)) {
         const propSchema = schema[propertyName];
-        const { attributeName = propertyName } = propSchema;
         if (propSchema) {
+            const { attributeName = propertyName } = propSchema;
             key[attributeName] = marshallValue(
                 propSchema,
                 startKey[propertyName]