diff --git a/neutron/cmd/sanity/checks.py b/neutron/cmd/sanity/checks.py
index 3810d1fa03a..f2958130352 100644
--- a/neutron/cmd/sanity/checks.py
+++ b/neutron/cmd/sanity/checks.py
@@ -154,7 +154,7 @@ def _vf_management_support(required_caps):
                    vf_section, cap):
                 is_supported = False
                 LOG.debug("ip link command does not support "
-                          "vf capability '%(cap)s'", cap)
+                          "vf capability '%(cap)s'", {'cap': cap})
     except ip_link_support.UnsupportedIpLinkCommand:
         LOG.exception(_LE("Unexpected exception while checking supported "
                           "ip link command"))