diff --git a/scripts/imgtool.py b/scripts/imgtool.py
index 4f5e56b..8a3e233 100755
--- a/scripts/imgtool.py
+++ b/scripts/imgtool.py
@@ -30,7 +30,8 @@
 
 def do_sign(args):
     align = args.align
-    # print('sign:', args)
+    if args.rsa_pkcs1_15:
+        keys.sign_rsa_pss = False
     img = image.Image.load(args.infile, version=args.version,
             header_size=args.header_size,
             pad=args.pad)
@@ -80,6 +81,8 @@
     sign.add_argument("-H", "--header-size", type=intparse, required=True)
     sign.add_argument("--pad", type=intparse,
             help='Pad image to this many bytes, adding trailer magic')
+    sign.add_argument("--rsa-pkcs1-15", help='Use old PKCS#1 v1.5 signature algorithm',
+            default=False, action='store_true')
     sign.add_argument("infile")
     sign.add_argument("outfile")