diff --git a/util/m b/util/m
index 4ec11f32806d3ab02dc5f9572af7928b9174aa78..860eeb05f408e819816ebda0613cdb0a1c0b8a9d 100755
--- a/util/m
+++ b/util/m
@@ -35,9 +35,9 @@ fi
 
 # Check whether host should be running in a chroot dir
 rootdir="/var/run/mn/$host/root"
-if [ -d $rootdir ]; then
+if [ -d $rootdir -a -x $rootdir/bin/bash ]; then
     cmd="'cd `pwd`; exec $cmd'"
-    cmd="chroot $rootdir bash -c $cmd"
+    cmd="chroot $rootdir /bin/bash -c $cmd"
 fi
 
 cmd="exec sudo mnexec -a $pid $cg $cmd"