diff --git a/scripts/imgtool.py b/scripts/imgtool.py
index d496d0f..6f0fb4e 100755
--- a/scripts/imgtool.py
+++ b/scripts/imgtool.py
@@ -9,7 +9,7 @@
 def gen_rsa2048(args):
     keys.RSA2048.generate().export_private(args.key)
 def gen_ecdsa_p256(args):
-    keys.ecdsa256p1.generate().export_private(args.key)
+    keys.ECDSA256P1.generate().export_private(args.key)
 def gen_ecdsa_p224(args):
     print("TODO: p-224 not yet implemented")