diff --git a/lib/classes/GraphStream.ts b/lib/classes/GraphStream.ts
index 1f0cb11..6bcc1ff 100644
--- a/lib/classes/GraphStream.ts
+++ b/lib/classes/GraphStream.ts
@@ -51,7 +51,7 @@ export class GraphStream extends Transform {
     }
     if (!states.includes (this._state)) {
       throw new Error (`invalid state to execute command ${instr}
-  expected: ${states.join (', ')}`);
+  expected: ${states.join (', ')}
   actual: ${this._state}`);
     }
   }