Index: virt-manager-0.10.0/virtinst/CapabilitiesParser.py
===================================================================
--- virt-manager-0.10.0.orig/virtinst/CapabilitiesParser.py
+++ virt-manager-0.10.0/virtinst/CapabilitiesParser.py
@@ -130,7 +130,9 @@ class CPUValues(object):
             child = child.next
 
     def get_arch(self, arch):
-        if re.match(r'i[4-9]86', arch):
+        if arch is None:
+            arch = "x86"
+        elif re.match(r'i[4-9]86', arch):
             arch = "x86"
         elif arch == "x86_64":
             arch = "x86"