diff --git a/libvirt.spec.in b/libvirt.spec.in
index 37a9ea48cb..c2e2be4a83 100644
--- a/libvirt.spec.in
+++ b/libvirt.spec.in
@@ -1728,8 +1728,37 @@ fi
     %if %{with_network}
 %post daemon-config-network
 if test $1 -eq 1 && test ! -f %{_sysconfdir}/libvirt/qemu/networks/default.xml ; then
+    # see if the network used by default network creates a conflict,
+    # and try to resolve it
+    # NB: 192.168.122.0/24 is used in the default.xml template file;
+    # do not modify any of those values here without also modifying
+    # them in the template.
+    orig_sub=122
+    sub=${orig_sub}
+    nl='
+'
+    routes="${nl}$(ip route show | cut -d' ' -f1)"
+    case ${routes} in
+      *"${nl}192.168.${orig_sub}.0/24${nl}"*)
+        # there was a match, so we need to look for an unused subnet
+        for new_sub in $(seq 124 254); do
+          case ${routes} in
+          *"${nl}192.168.${new_sub}.0/24${nl}"*)
+            ;;
+          *)
+            sub=$new_sub
+            break;
+            ;;
+          esac
+        done
+        ;;
+      *)
+        ;;
+    esac
+
     UUID=`/usr/bin/uuidgen`
-    sed -e "s,</name>,</name>\n  <uuid>$UUID</uuid>," \
+    sed -e "s/${orig_sub}/${sub}/g" \
+        -e "s,</name>,</name>\n  <uuid>$UUID</uuid>," \
          < %{_datadir}/libvirt/networks/default.xml \
          > %{_sysconfdir}/libvirt/qemu/networks/default.xml
     ln -s ../default.xml %{_sysconfdir}/libvirt/qemu/networks/autostart/default.xml