diff --git a/package.json b/package.json
index afe8a7f..2803713 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "aws-api-gateway-client",
-  "version": "0.3.2",
+  "version": "0.3.3",
   "description": "A module for AWS API Gateway client",
   "repository": {
     "type": "git",
diff --git a/src/lib/apiGatewayCore/sigV4Client.js b/src/lib/apiGatewayCore/sigV4Client.js
index 25ab807..c7cefc8 100755
--- a/src/lib/apiGatewayCore/sigV4Client.js
+++ b/src/lib/apiGatewayCore/sigV4Client.js
@@ -67,7 +67,7 @@ sigV4ClientFactory.newClient = function(config) {
 
     let sortedQueryParams = [];
     for (let property in queryParams) {
-      if (Object.prototype.hasOwnProperty.call(queryParams, "property")) {
+      if (Object.prototype.hasOwnProperty.call(queryParams, property)) {
         sortedQueryParams.push(property);
       }
     }
@@ -91,7 +91,7 @@ sigV4ClientFactory.newClient = function(config) {
     let canonicalHeaders = '';
     let sortedKeys = [];
     for (let property in headers) {
-      if (Object.prototype.hasOwnProperty.call(headers, "property")) {
+      if (Object.prototype.hasOwnProperty.call(headers, property)) {
         sortedKeys.push(property);
       }
     }
@@ -106,7 +106,7 @@ sigV4ClientFactory.newClient = function(config) {
   function buildCanonicalSignedHeaders(headers) {
     let sortedKeys = [];
     for (let property in headers) {
-      if (Object.prototype.hasOwnProperty.call(headers, "property")) {
+      if (Object.prototype.hasOwnProperty.call(headers, property)) {
         sortedKeys.push(property.toLowerCase());
       }
     }
diff --git a/src/lib/apiGatewayCore/simpleHttpClient.js b/src/lib/apiGatewayCore/simpleHttpClient.js
index db4ff58..f9074cc 100755
--- a/src/lib/apiGatewayCore/simpleHttpClient.js
+++ b/src/lib/apiGatewayCore/simpleHttpClient.js
@@ -27,7 +27,7 @@ simpleHttpClientFactory.newClient = (config) => {
 
     let canonicalQueryString = '';
     for (let property in queryParams) {
-      if (Object.prototype.hasOwnProperty.call(queryParams, "property")) {
+      if (Object.prototype.hasOwnProperty.call(queryParams, property)) {
         canonicalQueryString += encodeURIComponent(property)
           + '=' + encodeURIComponent(queryParams[property]) + '&';
       }
diff --git a/src/lib/apiGatewayCore/utils.js b/src/lib/apiGatewayCore/utils.js
index d2b59fa..a2f8bd0 100755
--- a/src/lib/apiGatewayCore/utils.js
+++ b/src/lib/apiGatewayCore/utils.js
@@ -63,7 +63,7 @@ const utils = {
     let copy = obj.constructor();
     let attr = null;
     for (attr in obj) {
-      if (Object.prototype.hasOwnProperty.call(obj, "attr")) copy[attr] = obj[attr];
+      if (Object.prototype.hasOwnProperty.call(obj, attr)) copy[attr] = obj[attr];
     }
     return copy;
   },
@@ -72,11 +72,11 @@ const utils = {
     let merged = baseObj.constructor();
     let attr = null;
     for (attr in baseObj) {
-      if (Object.prototype.hasOwnProperty.call(baseObj, "attr")) merged[attr] = baseObj[attr];
+      if (Object.prototype.hasOwnProperty.call(baseObj, attr)) merged[attr] = baseObj[attr];
     }
     if (null == additionalProps || 'object' != typeof additionalProps) return baseObj;
     for (attr in additionalProps) {
-      if (Object.prototype.hasOwnProperty.call(additionalProps, "attr")) {
+      if (Object.prototype.hasOwnProperty.call(additionalProps, attr)) {
         merged[attr] = additionalProps[attr];
       }
     }