diff --git a/src/index.ts b/src/index.ts
index d6b6298..6dc2a0c 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -226,23 +226,19 @@ export default class Config {
     key = key.replace(/-/g, "");
     key = key.toLowerCase();
 
-    if (this.hash[key] !== null) {
+    if (key in this.hash && this.hash[key] !== null) {
       return true;
     }
-
-    if (this.query[key] !== null) {
+    if (key in this.query && this.query[key] !== null) {
       return true;
     }
-
-    if (this.args[key] !== null) {
+    if (key in this.args && this.args[key] !== null) {
       return true;
     }
-
-    if (this.env[key] !== null) {
+    if (key in this.env && this.env[key] !== null) {
       return true;
     }
-
-    if (this.data[key] !== null) {
+    if (key in this.data && this.data[key] !== null) {
       return true;
     }
 
@@ -280,27 +276,22 @@ export default class Config {
     key = key.replace(/-/g, "");
     key = key.toLowerCase();
 
-    if (this.hash[key] !== null) {
+    if (key in this.hash && this.hash[key] !== null) {
       return this.hash[key];
     }
-
-    if (this.query[key] !== null) {
+    if (key in this.query && this.query[key] !== null) {
       return this.query[key];
     }
-
-    if (this.args[key] !== null) {
+    if (key in this.args && this.args[key] !== null) {
       return this.args[key];
     }
-
-    if (this.env[key] !== null) {
+    if (key in this.env && this.env[key] !== null) {
       return this.env[key];
     }
-
-    if (this.data[key] !== null) {
+    if (key in this.data && this.data[key] !== null) {
       return this.data[key];
     }
-
-    if (this.options[key] !== null) {
+    if (key in this.options && this.options[key] !== null) {
       return this.options[key];
     }