diff --git a/ChangeLog b/ChangeLog
index 0d5c8369f..92cb29d57 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-04-12  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	* util/grub-mkimage.c: Document memdisk implying --prefix.
+
 2013-04-12  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	* grub-core/bus/usb/ehci.c (grub_ehci_fini_hw): Ignore errors, not
diff --git a/util/grub-mkimage.c b/util/grub-mkimage.c
index dce2c295d..80e7d8113 100644
--- a/util/grub-mkimage.c
+++ b/util/grub-mkimage.c
@@ -1710,7 +1710,9 @@ static struct argp_option options[] = {
   {"memdisk",  'm', N_("FILE"), 0,
    /* TRANSLATORS: "memdisk" here isn't an identifier, it can be translated.
     "embed" is a verb (command description).  "*/
-   N_("embed FILE as a memdisk image"), 0},
+   N_("embed FILE as a memdisk image\n"
+      "Implies `-p (memdisk)/boot/grub' but prefix can be overridden by "
+      "later options"), 0},
    /* TRANSLATORS: "embed" is a verb (command description).  "*/
   {"config",   'c', N_("FILE"), 0, N_("embed FILE as an early config"), 0},
    /* TRANSLATORS: "embed" is a verb (command description).  "*/