diff --git a/cg-merge b/cg-merge
--- a/cg-merge
+++ b/cg-merge
@@ -48,7 +48,7 @@ branch=$(commit-id "$branchname") || exi
 
 [ -s $_git/blocked ] && die "merge blocked: $(cat $_git/blocked)"
 
-if grep -q "$branch" $_git/merging; then
+if grep -sq "$branch" $_git/merging; then
 	echo "Branch already merged in the working tree." >&2
 	echo 0
 fi