diff --git a/assembly/decoder.ts b/assembly/decoder.ts
index 45430d4..2edb455 100644
--- a/assembly/decoder.ts
+++ b/assembly/decoder.ts
@@ -57,7 +57,7 @@ export class ThrowingJSONHandler extends JSONHandler {
     }
 
     pushArray(name: string): bool {
-        assert(false, 'Unexpected array field' + name);
+        assert(false, 'Unexpected array field ' + name);
         return true;
     }