diff --git a/tests/merge/merge.sh b/tests/merge/merge.sh
--- a/tests/merge/merge.sh
+++ b/tests/merge/merge.sh
@@ -93,17 +93,17 @@ merge_init()
   CONFLICT1DIR=conflict1
   CONFLICT2DIR=conflict2
   mkdir ${CONFLICT1DIR}
   mkdir ${CONFLICT2DIR}
   # in the upgrade mode (dbm->sql), make sure our test databases
   # are dbm databases.
   if [ "${TEST_MODE}" = "UPGRADE_DB" ]; then
 	save=${NSS_DEFAULT_DB_TYPE}
-	NSS_DEFAULT_DB_TYPE= ; export NSS_DEFAULT_DB_TYPE
+	NSS_DEFAULT_DB_TYPE=dbm ; export NSS_DEFAULT_DB_TYPE
   fi
 
   certutil -N -d ${CONFLICT1DIR} -f ${R_PWFILE}
   certutil -N -d ${CONFLICT2DIR} -f ${R_PWFILE}
   certutil -A -n Alice -t ,, -i ${R_CADIR}/TestUser41.cert -d ${CONFLICT1DIR}
   # modify CONFLICTDIR potentially corrupting the database
   certutil -A -n "Alice #1" -t C,, -i ${R_CADIR}/TestUser42.cert -d ${CONFLICT1DIR} -f ${R_PWFILE}
   certutil -M -n "Alice #1" -t ,, -d ${CONFLICT1DIR} -f ${R_PWFILE}