diff --git a/linux/workaround_CVE-2009-2692.sh b/linux/workaround_CVE-2009-2692.sh
index 2d7beb5..2b4dbf4 100755
--- a/linux/workaround_CVE-2009-2692.sh
+++ b/linux/workaround_CVE-2009-2692.sh
@@ -20,7 +20,11 @@
 # Idea based on data from D-INFK ISG (www.isg.inf.ethz.ch)
 #
 
-cat << eof >> /etc/modprobe.d/aliases
+string="# workaround for CVE-2009-2692"
+file="/etc/modprobe.d/aliases"
+
+grep "^$string" "$file" >/dev/null || cat << eof >> "$file"
+$string
 alias net-pf-10 off
 alias ipv6 off
 alias ib_ipoib off