diff --git a/src/main/scala/li/cil/oc/server/driver/Registry.scala b/src/main/scala/li/cil/oc/server/driver/Registry.scala
index 9019640b66..82d4b8de83 100644
--- a/src/main/scala/li/cil/oc/server/driver/Registry.scala
+++ b/src/main/scala/li/cil/oc/server/driver/Registry.scala
@@ -157,7 +157,7 @@ private[oc] object Registry extends api.detail.DriverAPI {
     }
     else {
       valueRef match {
-        case null | None => null
+        case null | () | None => null
         case arg: java.lang.Boolean => arg
         case arg: java.lang.Byte => arg
         case arg: java.lang.Character => arg