diff --git a/mininet/util.py b/mininet/util.py
index 8fe3f368a3f4c02bec5b27031662cbddd52b006d..6016cd3cd5a804629cace815bae6d6d62da5fb85 100644
--- a/mininet/util.py
+++ b/mininet/util.py
@@ -316,8 +316,8 @@ def mountCgroups():
     if 'cgroups on %s' % cgdir not in mounts:
         raise Exception( "cgroups not mounted on " + cgdir )
     if 'cpuset on %s' % csdir not in mounts:
-        errRun( 'mkdir -p', csdir )
-        errRun( 'mount -t cgroup -ocpuset cpuset', csdir )
+        errRun( 'mkdir -p ' + csdir )
+        errRun( 'mount -t cgroup -ocpuset cpuset ' + csdir )
 
 def natural( text ):
     "To sort sanely/alphabetically: sorted( l, key=natural )"