diff --git a/src/virtManager/details.py b/src/virtManager/details.py
index b14937c9c..10215aff9 100644
--- a/src/virtManager/details.py
+++ b/src/virtManager/details.py
@@ -1837,10 +1837,9 @@ class vmmDetails(vmmGObjectUI):
         net_bridge = self.window.get_widget("network-bridge")
         nettype, source = uihelpers.get_network_selection(net_list, net_bridge)
 
+        source_mode = None
         if (nettype  == "direct"):
             source_mode = self.get_combo_label_value("network-source-mode")
-        else:
-            source_mode = ""
 
         model = self.get_combo_label_value("network-model")
 
diff --git a/src/virtManager/domain.py b/src/virtManager/domain.py
index 87602fd63..4f97e6114 100644
--- a/src/virtManager/domain.py
+++ b/src/virtManager/domain.py
@@ -543,9 +543,10 @@ class vmmDomain(vmmLibvirtObject):
             if not newtype:
                 return
             editdev.source = None
+
             editdev.type = newtype
             editdev.source = newsource
-            editdev.source_mode = newmode
+            editdev.source_mode = newmode or None
         return self._redefine_device(change, devobj)
     def define_network_model(self, devobj, newmodel):
         def change(editdev):
diff --git a/src/virtManager/uihelpers.py b/src/virtManager/uihelpers.py
index 9dc51bd31..1dc482fe1 100644
--- a/src/virtManager/uihelpers.py
+++ b/src/virtManager/uihelpers.py
@@ -209,10 +209,10 @@ def populate_source_mode_combo(vm, combo):
 
     # [xml value, label]
     model.append([None, _("")])
-    model.append(["vepa", "vepa"])
-    model.append(["bridge", "bridge"])
-    model.append(["private", "private"])
-    model.append(["passthrough", "passthrough"])
+    model.append(["vepa", "VEPA"])
+    model.append(["bridge", "Bridge"])
+    model.append(["private", "Private"])
+    model.append(["passthrough", "Passthrough"])
 
 def build_netmodel_combo(vm, combo):
     dev_model = gtk.ListStore(str, str)
diff --git a/src/vmm-details.glade b/src/vmm-details.glade
index 5861a86b6..e4d970306 100644
--- a/src/vmm-details.glade
+++ b/src/vmm-details.glade
@@ -3721,7 +3721,6 @@ I/O:</property>
                                             <child>
                                               <widget class="GtkHBox" id="network-source-mode-box">
                                                 <property name="visible">True</property>
-                                                <property name="spacing">6</property>
                                                 <child>
                                                   <widget class="GtkComboBox" id="network-source-mode-combo">
                                                     <property name="visible">True</property>
@@ -3762,6 +3761,7 @@ I/O:</property>
                                               <packing>
                                                 <property name="top_attach">3</property>
                                                 <property name="bottom_attach">4</property>
+                                                <property name="x_options">GTK_FILL</property>
                                               </packing>
                                             </child>
                                           </widget>