diff --git a/contrib/thunderbird-patch-inline/appp.sh b/contrib/thunderbird-patch-inline/appp.sh
index 1053872eea..fdcc948352 100755
--- a/contrib/thunderbird-patch-inline/appp.sh
+++ b/contrib/thunderbird-patch-inline/appp.sh
@@ -31,7 +31,7 @@ BODY=$(sed -e "1,/${SEP}/d" $1)
 CMT_MSG=$(sed -e '1,/^$/d' -e '/^---$/,$d' "${PATCH}")
 DIFF=$(sed -e '1,/^---$/d' "${PATCH}")
 
-CCS=$(echo -e "$CMT_MSG\n$HEADERS" | sed -n -e 's/^Cc: \(.*\)$/\1,/gp' \
+CCS=$(printf '%s\n%s\n' "$CMT_MSG" "$HEADERS" | sed -n -e 's/^Cc: \(.*\)$/\1,/gp' \
 	-e 's/^Signed-off-by: \(.*\)/\1,/gp')
 
 echo "$SUBJECT" > $1