diff --git a/src/main/java/org/caosdb/server/grpc/CaosDBToGrpcConverters.java b/src/main/java/org/caosdb/server/grpc/CaosDBToGrpcConverters.java
index fe09df562663289fd796c79bc1db30875e266da5..6d1beea5de3ed107d45e03fe6461e9999402b3a2 100644
--- a/src/main/java/org/caosdb/server/grpc/CaosDBToGrpcConverters.java
+++ b/src/main/java/org/caosdb/server/grpc/CaosDBToGrpcConverters.java
@@ -299,7 +299,7 @@ public class CaosDBToGrpcConverters {
   }
 
   private ScalarValue convertScalarValue(final IndexedSingleValue v) {
-    if (v == null) {
+    if (v == null || v.getWrapped() == null) {
       return ScalarValue.newBuilder()
           .setSpecialValue(SpecialValue.SPECIAL_VALUE_UNSPECIFIED)
           .build();