diff --git a/src/app/component/layout/toolbar/scanner-setting-dropdown.component.ts b/src/app/component/layout/toolbar/scanner-setting-dropdown.component.ts
index 922a699..0ae2201 100644
--- a/src/app/component/layout/toolbar/scanner-setting-dropdown.component.ts
+++ b/src/app/component/layout/toolbar/scanner-setting-dropdown.component.ts
@@ -130,7 +130,11 @@ export class ScannerSettingDropdownComponent implements OnInit, OnDestroy {
   }
 
   portPressed(evt: KeyboardEvent) {
-    if (!Number.isInteger(Number(evt.key))) {
+    const portNum = Number(evt.key);
+    if (portNum === 0) {
+      return false;
+    }
+    if (!Number.isInteger(portNum)) {
       return false;
     }
   }