diff --git a/src/nim_lk.nim b/src/nim_lk.nim
index 09ced9d..45c5ddc 100644
--- a/src/nim_lk.nim
+++ b/src/nim_lk.nim
@@ -573,7 +573,7 @@ proc update(bom: JsonNode; bomRef: string; byName: bool): bool =
   let comp = bom.getComponent(bomRef, byName)
   assert not comp.isNil
   var bomRef = comp{"bom-ref"}.getStr
-  assert not bomRef.isNil
+  assert bomRef != ""
   var suitableRefFound = false
   let extRefs = comp{"externalReferences"}
   for extRef in extRefs.elems: