diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 257a1ea93b..72eccde3c9 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -2819,7 +2819,7 @@ virDomainNetDefParseXML(virCapsPtr caps,
                 ifname = virXMLPropString(cur, "dev");
                 if ((ifname != NULL) &&
                     ((flags & VIR_DOMAIN_XML_INACTIVE) &&
-                      (STRPREFIX((const char*)ifname, "vnet")))) {
+                      (STRPREFIX(ifname, VIR_NET_GENERATED_PREFIX)))) {
                     /* An auto-generated target name, blank it out */
                     VIR_FREE(ifname);
                 }
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index c748f5211c..dd33eb0607 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -429,6 +429,10 @@ struct _virDomainNetDef {
     virBandwidthPtr bandwidth;
 };
 
+/* Used for prefix of ifname of any network name generated dynamically
+ * by libvirt, and cannot be used for a persistent network name.  */
+# define VIR_NET_GENERATED_PREFIX "vnet"
+
 enum virDomainChrDeviceType {
     VIR_DOMAIN_CHR_DEVICE_TYPE_PARALLEL = 0,
     VIR_DOMAIN_CHR_DEVICE_TYPE_SERIAL,
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index ee42f1db72..6a2e2ae27c 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -188,7 +188,7 @@ qemuNetworkIfaceConnect(virDomainDefPtr def,
     int err;
     int tapfd = -1;
     int vnet_hdr = 0;
-    int template_ifname = 0;
+    bool template_ifname = false;
     unsigned char tapmac[VIR_MAC_BUFLEN];
     int actualType = virDomainNetGetActualType(net);
 
@@ -244,15 +244,15 @@ qemuNetworkIfaceConnect(virDomainDefPtr def,
     }
 
     if (!net->ifname ||
-        STRPREFIX(net->ifname, "vnet") ||
+        STRPREFIX(net->ifname, VIR_NET_GENERATED_PREFIX) ||
         strchr(net->ifname, '%')) {
         VIR_FREE(net->ifname);
-        if (!(net->ifname = strdup("vnet%d"))) {
+        if (!(net->ifname = strdup(VIR_NET_GENERATED_PREFIX "%d"))) {
             virReportOOMError();
             goto cleanup;
         }
         /* avoid exposing vnet%d in getXMLDesc or error outputs */
-        template_ifname = 1;
+        template_ifname = true;
     }
 
     if (qemuCapsGet(qemuCaps, QEMU_CAPS_VNET_HDR) &&
diff --git a/src/uml/uml_conf.c b/src/uml/uml_conf.c
index 417271ee9c..7b5e094c4d 100644
--- a/src/uml/uml_conf.c
+++ b/src/uml/uml_conf.c
@@ -115,7 +115,7 @@ umlConnectTapDevice(virConnectPtr conn,
                     const char *bridge)
 {
     brControl *brctl = NULL;
-    int template_ifname = 0;
+    bool template_ifname = false;
     int err;
     unsigned char tapmac[VIR_MAC_BUFLEN];
 
@@ -126,13 +126,13 @@ umlConnectTapDevice(virConnectPtr conn,
     }
 
     if (!net->ifname ||
-        STRPREFIX(net->ifname, "vnet") ||
+        STRPREFIX(net->ifname, VIR_NET_GENERATED_PREFIX) ||
         strchr(net->ifname, '%')) {
         VIR_FREE(net->ifname);
-        if (!(net->ifname = strdup("vnet%d")))
+        if (!(net->ifname = strdup(VIR_NET_GENERATED_PREFIX "%d")))
             goto no_memory;
         /* avoid exposing vnet%d in getXMLDesc or error outputs */
-        template_ifname = 1;
+        template_ifname = true;
     }
 
     memcpy(tapmac, net->mac, VIR_MAC_BUFLEN);