diff --git a/src/services/OpenAPIParser.ts b/src/services/OpenAPIParser.ts
index 6b36dc2a..a28dc837 100644
--- a/src/services/OpenAPIParser.ts
+++ b/src/services/OpenAPIParser.ts
@@ -35,7 +35,7 @@ export class OpenAPIParser {
 
     const href = IS_BROWSER ? window.location.href : '';
     if (typeof specUrl === 'string') {
-      this.specUrl = new URL(specUrl, href).href;
+      this.specUrl = href ? new URL(specUrl, href).href : specUrl;
     }
   }