diff --git a/contrib/clean-db b/contrib/clean-db
index 46efdcb..8f049f1 100755
--- a/contrib/clean-db
+++ b/contrib/clean-db
@@ -5,12 +5,15 @@ variant=$1;
 variant_ids=`echo "select id from variant where variant like '"${variant}"';" | mysql -N `
 variant_ids=`echo ${variant_ids} | tr " " ","`
 
-echo Delete variants $variant_ids
+echo Delete variants: $variant_ids
+
+if [ -n "$variant_ids" ]; then
 
 echo "delete from result_GenericExperimentMessage where pilot_id in (select id from fsppilot where variant_id in (${variant_ids}));" | mysql
 echo "delete from fspgroup where variant_id in (${variant_ids});" | mysql
 echo "delete from fsppilot where variant_id in (${variant_ids});" | mysql
 echo "delete from trace where variant_id in (${variant_ids});" | mysql
 
+fi