diff --git a/test/lib/check.sh b/test/lib/check.sh
index 6f56ea320..1ec1babab 100644
--- a/test/lib/check.sh
+++ b/test/lib/check.sh
@@ -148,7 +148,7 @@ mirror_nonredundant() {
 	attr=$(get lv_field "$lv" attr)
 	(echo "$attr" | grep "^......m...$" >/dev/null) || {
 		if (echo "$attr" | grep "^o.........$" >/dev/null) &&
-		   lvs -a | fgrep "[${2}_mimage" >/dev/null; then
+		   lvs -a | grep -F "[${2}_mimage" >/dev/null; then
 			echo "TEST WARNING: $lv is a snapshot origin and looks like a mirror,"
 			echo "assuming it is actually a mirror"
 		else