diff --git a/scripts/mbedtls_dev/bignum_data.py b/scripts/mbedtls_dev/bignum_data.py
index 9658933..0a48e53 100644
--- a/scripts/mbedtls_dev/bignum_data.py
+++ b/scripts/mbedtls_dev/bignum_data.py
@@ -121,6 +121,9 @@
 ONLY_PRIME_MODULI = [
         "53", # safe prime
         "8ac72304057392b5",     # 9999999997777777333 (longer, not safe, prime)
+        # The next prime has a different R in Montgomery form depending on
+        # whether 32- or 64-bit MPIs are used.
+        "152d02c7e14af67fe0bf", # 99999999999999999991999
         SAFE_PRIME_192_BIT_SEED_1,  # safe prime
         SAFE_PRIME_1024_BIT_SEED_3, # safe prime
         ]
diff --git a/scripts/mbedtls_dev/bignum_mod_raw.py b/scripts/mbedtls_dev/bignum_mod_raw.py
index 6fc4c91..0084898 100644
--- a/scripts/mbedtls_dev/bignum_mod_raw.py
+++ b/scripts/mbedtls_dev/bignum_mod_raw.py
@@ -61,7 +61,7 @@
     symbol = "^ -1"
     test_function = "mpi_mod_raw_inv_prime"
     test_name = "mbedtls_mpi_mod_raw_inv_prime (Montgomery form only)"
-    input_style = "fixed"
+    input_style = "arch_split"
     arity = 1
     suffix = True