diff --git a/mender-convert-modify b/mender-convert-modify
index 198ab45..68378cc 100755
--- a/mender-convert-modify
+++ b/mender-convert-modify
@@ -294,10 +294,10 @@ if [ "${MENDER_DATA_PART_GROWFS}" == "y" ]; then
 fi
 
 if echo ${MENDER_ROOT_PART_FSTAB_OPTS} | tr ',' '\n' | egrep -q "^ro$"; then
-  if ! echo "${MENDER_ROOT_PART_MKFS_OPTS}" | fgrep -q -- "-O ^64bit"; then
+  if ! echo "${MENDER_ROOT_PART_MKFS_OPTS}" | fgrep -q -- "^64bit"; then
     log_warn "EXT4 64bits feature is known to create unstable checksums on read-only file systems, add \"-O ^64bit\" to MENDER_ROOT_PART_MKFS_OPTS to remove it"
   fi
-  if ! echo "${MENDER_ROOT_PART_MKFS_OPTS}" | fgrep -q -- "-O ^has_journal"; then
+  if ! echo "${MENDER_ROOT_PART_MKFS_OPTS}" | fgrep -q -- "^has_journal"; then
     log_warn "EXT4 journal feature is known to create unstable checksums on read-only file systems, add \"-O ^has_journal\" to MENDER_ROOT_PART_MKFS_OPTS to remove it"
   fi
 fi