--- a/munin-node.in
+++ b/munin-node.in
@@ -141,7 +141,7 @@
   fi
 }
 fetch_if() {
-  IINFO=$(grep "$1:" /proc/net/dev | cut -d: -f2 | sed -e 's/  / /g')
+  IINFO=$(sed -ne "/^ *${1//_/-}: / { s/^.\+: \+//; s/[[:space:]]\+/ /gp }" /proc/net/dev)
   echo "down.value" $(echo $IINFO | cut -d\  -f1)
   echo "up.value" $(echo $IINFO | cut -d\  -f9)
 }
@@ -162,7 +162,7 @@
   echo "trans.warning 1"
 }
 fetch_if_err() {
-  IINFO=$(grep "$1:" /proc/net/dev | cut -d: -f2 | sed -e 's/  / /g')
+  IINFO=$(sed -ne "/^ *${1//_/-}: / { s/^.\+: \+//; s/[[:space:]]\+/ /gp }" /proc/net/dev)
   echo "rcvd.value" $(echo $IINFO | cut -d\  -f3)
   echo "trans.value" $(echo $IINFO | cut -d\  -f11)
 }