diff --git a/tests-extra/tools/dnstest/zonefile.py b/tests-extra/tools/dnstest/zonefile.py
index 19c6f45e374ac055bfbc1174ccc25c16687f1bde..aa894c7562abd402118a03ae6a5ed1ce996c8ab5 100644
--- a/tests-extra/tools/dnstest/zonefile.py
+++ b/tests-extra/tools/dnstest/zonefile.py
@@ -118,7 +118,7 @@ class ZoneFile(object):
 
         # note: convert origin to lower case due to a bug in dnssec-verify
         origin = self.name.lower()
-        cmd = Popen(["dnssec-verify", "-o", origin, self.path],
+        cmd = Popen(["dnssec-verify", "-z", "-o", origin, self.path],
                     stdout=PIPE, stderr=PIPE, universal_newlines=True)
         (out, err) = cmd.communicate()