diff --git a/src/serializer.js b/src/serializer.js
index b23c06c33..b37875895 100644
--- a/src/serializer.js
+++ b/src/serializer.js
@@ -561,6 +561,8 @@ export class Serializer {
         return str
       case 'NamedNode':
         return this.symbolToN3(expr)
+      case 'DefaultGraph':
+        return '';
       default:
         throw new Error('Internal: atomicTermToN3 cannot handle ' + expr + ' of termType: ' + expr.termType)
     }