diff --git a/src/mol-model/structure/structure/element.ts b/src/mol-model/structure/structure/element.ts
index 39ef7d4e0b2250a004967de3ad0ec418f41d1022..200f8b4c06a34edacdc3e801d6a3841a9d2fcae2 100644
--- a/src/mol-model/structure/structure/element.ts
+++ b/src/mol-model/structure/structure/element.ts
@@ -368,7 +368,7 @@ namespace StructureElement {
             }
 
             return MS.struct.modifier.union([
-                byOpName.length === 1 ? byOpName[0] : MS.struct.combinator.merge.apply(null, byOpName)
+                byOpName.length === 1 ? byOpName[0] : MS.struct.combinator.merge(byOpName)
             ]);
         }