diff --git a/packages/actor-rdf-join-incremental-optional-hash/lib/IncrementalOptionalHash.ts b/packages/actor-rdf-join-incremental-optional-hash/lib/IncrementalOptionalHash.ts
index 09854d34..3b7c251e 100644
--- a/packages/actor-rdf-join-incremental-optional-hash/lib/IncrementalOptionalHash.ts
+++ b/packages/actor-rdf-join-incremental-optional-hash/lib/IncrementalOptionalHash.ts
@@ -50,7 +50,7 @@ export class IncrementalOptionalHash extends IncrementalInnerJoin {
       return false;
     }
 
-    if (array.length < 2 && array[0].equals(item)) {
+    if (array.length == 1 && array[0].equals(item)) {
       memory.delete(hash);
       return true;
     }