diff --git a/hyper-v.changes b/hyper-v.changes
index aea2585..d5faa2d 100644
--- a/hyper-v.changes
+++ b/hyper-v.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Mon May 26 15:50:21 CEST 2014 - ohering@suse.de
+
+- copy mask2pfxlen from /etc/sysconfig/network/scripts/functions
+  to hv_set_ifconfig (bnc#879256)
+
 -------------------------------------------------------------------
 Wed May 21 12:05:31 CEST 2014 - ohering@suse.de
 
diff --git a/hyper-v.tools.hv.hv_set_ifconfig.sh b/hyper-v.tools.hv.hv_set_ifconfig.sh
index e3ccd56..ae861d3 100644
--- a/hyper-v.tools.hv.hv_set_ifconfig.sh
+++ b/hyper-v.tools.hv.hv_set_ifconfig.sh
@@ -44,14 +44,37 @@ then
 fi
 # send subshell output to syslog
 (
-f=/etc/sysconfig/network/scripts/functions
-if test -f ${f}
-then
-	. ${f}
-else
-	echo "MISSING ${f}"
-	exit 1
-fi
+# copied from /etc/sysconfig/network/scripts/functions
+mask2pfxlen() {
+	local i octet width=0 mask=(${1//./ })
+	test ${#mask[@]} -eq 4 || return 1
+	for octet in 0 1 2 3
+	do
+		test "${mask[octet]}" -ge 0 -a "${mask[octet]}" -le 255 || return 1
+		for i in 128 192 224 240 248 252 254 255
+		do
+			test ${mask[octet]} -ge $i && ((width++))
+		done
+	done
+	echo $width
+	return 0
+}
+
+pfxlen2mask() {
+	test -n "$1" || return 1
+	local o i n=0 adr=() len=$(($1))
+	for o in 0 1 2 3
+	do
+		adr[$o]=0
+		for i in 128 64 32 16 8 4 2 1
+		do
+			((n++ < len)) && ((adr[$o] = ${adr[$o]} + $i))
+		done
+	done
+	echo ${adr[0]}.${adr[1]}.${adr[2]}.${adr[3]}
+	return 0
+}
+
 # remove known config variables from environment 
 unset HWADDR
 unset BOOTPROTO