diff --git a/src/main/java/eu/openaire/api/mappers/Utils.java b/src/main/java/eu/openaire/api/mappers/Utils.java
index 507a23e..fdced3f 100644
--- a/src/main/java/eu/openaire/api/mappers/Utils.java
+++ b/src/main/java/eu/openaire/api/mappers/Utils.java
@@ -127,7 +127,7 @@ public class Utils {
 		// if the value starts with the NOT operator, add a wildcard at the beginning
 		// NOTE: this is a workaround for Solr, which does not support solely NOT queries
 		if (value.startsWith("NOT")) {
-			value = "*:* " + value;
+			value = "* " + value;
 		}
 
 		return value;