diff --git a/tools/mkimage.c b/tools/mkimage.c
index ab6ea32ad0..8a20594f31 100644
--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -229,6 +229,7 @@ main (int argc, char **argv)
 			case 'f':
 				if (--argc <= 0)
 					usage ();
+				params.type = IH_TYPE_FLATDT;
 				params.datafile = *++argv;
 				params.fflag = 1;
 				goto NXTARG;