diff --git a/n3/n3.d.ts b/n3/n3.d.ts
index 28debcb94b..8531a89258 100644
--- a/n3/n3.d.ts
+++ b/n3/n3.d.ts
@@ -94,7 +94,7 @@ declare module "n3" {
         }
 
         interface N3StoreWriter extends N3Writer {
-            find(subject: string, predicate: string | null, object: string | null): Triple[];
+            find(subject: string, predicate: string, object: string): Triple[];
         }
         function Store(): N3StoreWriter;