diff --git a/src/router/apiKeyManager.ts b/src/router/apiKeyManager.ts
index 12e5d23..e906490 100644
--- a/src/router/apiKeyManager.ts
+++ b/src/router/apiKeyManager.ts
@@ -10,10 +10,10 @@ export class ApiKeyManager {
    * Register an API key for a provider
    */
   public registerKey(provider: string, apiKey: string): void {
-    if (!provider || typeof provider !== 'string' || provider.trim() === '') {
+    if (!provider || typeof provider !== 'string' || provider.trim().length === 0) {
       throw new Error('TokenFirewall: Provider must be a non-empty string');
     }
-    if (!apiKey || typeof apiKey !== 'string' || apiKey.trim() === '') {
+    if (!apiKey || typeof apiKey !== 'string' || apiKey.trim().length === 0) {
       throw new Error(`TokenFirewall: Invalid API key for provider "${provider}"`);
     }
     this.keys.set(provider.toLowerCase(), apiKey);
diff --git a/src/router/modelRouter.ts b/src/router/modelRouter.ts
index 4b6f8ea..de6a573 100644
--- a/src/router/modelRouter.ts
+++ b/src/router/modelRouter.ts
@@ -64,7 +64,7 @@ export class ModelRouter {
         
         // Validate each fallback model name
         for (const fallbackModel of fallbacks) {
-          if (typeof fallbackModel !== 'string' || fallbackModel.trim() === '') {
+          if (typeof fallbackModel !== 'string' || fallbackModel.trim().length === 0) {
             throw new Error(
               `TokenFirewall Router: fallbackMap for "${model}" contains invalid model name (empty or whitespace)`
             );