diff --git a/src/xenconfig/xen_xl.c b/src/xenconfig/xen_xl.c
index 4f24d457c8c60e6d84453d738fa867a8e769a89f..cac440cd450bd064cf6aba40ac11786501867f46 100644
--- a/src/xenconfig/xen_xl.c
+++ b/src/xenconfig/xen_xl.c
@@ -316,6 +316,10 @@ xenParseXLDiskSrc(virDomainDiskDefPtr disk, char *srcstr)
     char *tmpstr = NULL;
     int ret = -1;
 
+    /* A NULL source is valid, e.g. an empty CDROM */
+    if (srcstr == NULL)
+        return 0;
+
     if (STRPREFIX(srcstr, "rbd:")) {
         if (!(tmpstr = virStringReplace(srcstr, "\\\\", "\\")))
             goto cleanup;
diff --git a/tests/xlconfigdata/test-disk-positional-parms-partial.cfg b/tests/xlconfigdata/test-disk-positional-parms-partial.cfg
index fd16db04c19894835e8746a710e0659360ee1e43..940304e7b2187cef3b6b9d9c42a202d2c8dfc4f7 100644
--- a/tests/xlconfigdata/test-disk-positional-parms-partial.cfg
+++ b/tests/xlconfigdata/test-disk-positional-parms-partial.cfg
@@ -22,4 +22,4 @@ parallel = "none"
 serial = "none"
 builder = "hvm"
 boot = "d"
-disk = [ "/dev/HostVG/XenGuest2,,hda,,backendtype=phy", "/var/lib/libvirt/images/XenGuest2-home,,hdb,,", "/root/boot.iso,,hdc,,devtype=cdrom" ]
+disk = [ "/dev/HostVG/XenGuest2,,hda,,backendtype=phy", "/var/lib/libvirt/images/XenGuest2-home,,hdb,,", "/root/boot.iso,,hdc,,devtype=cdrom" , "format=raw,vdev=hdd,access=ro,devtype=cdrom" ]
diff --git a/tests/xlconfigdata/test-disk-positional-parms-partial.xml b/tests/xlconfigdata/test-disk-positional-parms-partial.xml
index e86a5be192891493b1641bbe9a0016cce2def268..52b21dc59247bb40b1f958f6ac7f60688cf1ce4a 100644
--- a/tests/xlconfigdata/test-disk-positional-parms-partial.xml
+++ b/tests/xlconfigdata/test-disk-positional-parms-partial.xml
@@ -39,6 +39,12 @@
       <readonly/>
       <address type='drive' controller='0' bus='1' target='0' unit='0'/>
     </disk>
+    <disk type='file' device='cdrom'>
+      <driver name='qemu' type='raw'/>
+      <target dev='hdd' bus='ide'/>
+      <readonly/>
+      <address type='drive' controller='0' bus='1' target='0' unit='1'/>
+    </disk>
     <controller type='ide' index='0'/>
     <interface type='bridge'>
       <mac address='00:16:3e:66:92:9c'/>