diff --git a/packages/grpc-js/src/resolver-dns.ts b/packages/grpc-js/src/resolver-dns.ts
index 2db8a5e4..3f28254b 100644
--- a/packages/grpc-js/src/resolver-dns.ts
+++ b/packages/grpc-js/src/resolver-dns.ts
@@ -268,7 +268,13 @@ class DnsResolver implements Resolver {
    * @param target
    */
   static getDefaultAuthority(target: GrpcUri): string {
-    return target.path;
+    const hostPort = uri_parser_1.splitHostPort(target.path);
+    if (hostPort !== null) {
+      return hostPort.host;
+    }
+    else {
+      throw new Error(`Failed to parse target ${uri_parser_1.uriToString(target)}`);
+    }
   }
 }