diff --git a/glance/store/filesystem.py b/glance/store/filesystem.py
index 5ad67f1..6c8ce66 100644
--- a/glance/store/filesystem.py
+++ b/glance/store/filesystem.py
@@ -356,7 +356,7 @@ class Store(glance.store.base.Store):
         """
 
         #Calculate total available space
-        df = processutils.execute("df", "-k",
+        df = processutils.execute("df", "-k","-P",
                                   mount_point)[0].strip("'\n'")
         total_available_space = int(df.split('\n')[1].split()[3]) * units.Ki