diff --git a/pelab/libnetmon/instrument-simple.sh b/pelab/libnetmon/instrument-simple.sh
index 0a14822f58018badce0cb0d1228ea498391e4653..a1eaf69fc459ca86bec6e56740f2f8e752cb4ec7 100755
--- a/pelab/libnetmon/instrument-simple.sh
+++ b/pelab/libnetmon/instrument-simple.sh
@@ -1,6 +1,7 @@
 #!/bin/sh
 export LD_LIBRARY_PATH=.:$LD_LIBRARY_PATH
 export LD_PRELOAD=libnetmon.so
+export LIBNETMON_MONITORUDP=1
 if [ "x$LIBNETMON_OUTPUTVERSION" = "x" ]; then
     export LIBNETMON_OUTPUTVERSION=3
 else