diff --git a/doc/mkimage.1 b/doc/mkimage.1
index d0a038a..c190389 100644
--- a/doc/mkimage.1
+++ b/doc/mkimage.1
@@ -281,8 +281,10 @@
 .BI \-B " alignment"
 .TQ
 .BI \-\-alignment " alignment"
-The alignment, in hexadecimal, that external data will be aligned to. This
-option only has an effect when \-E is specified.
+The alignment, in hexadecimal, that the FDT structure will be aligned
+to. With
+.BR \-E ,
+also specifies the alignment for the external data.
 .
 .TP
 .BI \-p " external-position"
diff --git a/tools/mkimage.c b/tools/mkimage.c
index 6dfe3e1..a5979fa 100644
--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -112,7 +112,7 @@
 		"          -f => input filename for FIT source\n"
 		"          -i => input filename for ramdisk file\n"
 		"          -E => place data outside of the FIT structure\n"
-		"          -B => align size in hex for FIT structure and header\n"
+		"          -B => align size in hex for FIT structure and, with -E, for the external data\n"
 		"          -b => append the device tree binary to the FIT\n"
 		"          -t => update the timestamp in the FIT\n");
 #ifdef CONFIG_FIT_SIGNATURE