diff --git a/meta/classes/qemuboot.bbclass b/meta/classes/qemuboot.bbclass
index 229bd88527..755d49acd6 100644
--- a/meta/classes/qemuboot.bbclass
+++ b/meta/classes/qemuboot.bbclass
@@ -136,6 +136,8 @@ python do_write_qemuboot_conf() {
                                'qemu-helper-native/1.0-r1/recipe-sysroot-native/usr/bin/')
         else:
             val = d.getVar(k)
+        if val is None:
+            continue
         # we only want to write out relative paths so that we can relocate images
         # and still run them
         if val.startswith(topdir):