diff --git a/scripts/mbedtls_dev/ecp.py b/scripts/mbedtls_dev/ecp.py
index c167f6b6ff..e0fb000354 100644
--- a/scripts/mbedtls_dev/ecp.py
+++ b/scripts/mbedtls_dev/ecp.py
@@ -81,7 +81,7 @@ class EcpP521R1Raw(bignum_common.ModOperationCommon,
     """Test cases for ecp quasi_reduction()."""
     test_function = "ecp_mod_p521_raw"
     test_name = "ecp_mod_p521_raw"
-    input_style = "fixed"
+    input_style = "arch_split"
     arity = 1
 
     moduli = [("01ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"