diff --git a/grub-core/kern/emu/hostdisk.c b/grub-core/kern/emu/hostdisk.c
index a3b00c8f6..610518d0c 100644
--- a/grub-core/kern/emu/hostdisk.c
+++ b/grub-core/kern/emu/hostdisk.c
@@ -422,7 +422,7 @@ read_device_map (const char *dev_map)
   char buf[1024];	/* XXX */
   int lineno = 0;
 
-  if (dev_map[0] == '\0')
+  if (!dev_map || dev_map[0] == '\0')
     {
       grub_util_info ("no device.map");
       return;