diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 98e2f9519..fe62fec4d 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -5420,7 +5420,7 @@ int mbedtls_ecp_mod_p521_raw(mbedtls_mpi_uint *X, size_t X_limbs)
 static int ecp_mod_p255(mbedtls_mpi *N)
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    size_t expected_width = 2 * ((256 + biL - 1) / biL);
+    size_t expected_width = 2 * ((255 + biL - 1) / biL);
     MBEDTLS_MPI_CHK(mbedtls_mpi_grow(N, expected_width));
     ret = mbedtls_ecp_mod_p255_raw(N->p, expected_width);
 cleanup:
@@ -5433,32 +5433,26 @@ int mbedtls_ecp_mod_p255_raw(mbedtls_mpi_uint *X, size_t X_Limbs)
     mbedtls_mpi_uint carry[P255_WIDTH];
     memset(carry, 0, sizeof(mbedtls_mpi_uint) * P255_WIDTH);
 
-    if (X_Limbs > 2*P255_WIDTH) {
-        X_Limbs = 2*P255_WIDTH;
-    } else if (X_Limbs < P255_WIDTH) {
-        return 0;
-    }
-
     /* Step 1: Reduction to P255_WIDTH limbs */
     if (X_Limbs > P255_WIDTH) {
-        /* Helper references for top part of N */
-        mbedtls_mpi_uint * const NT_p = X + P255_WIDTH;
-        const size_t NT_n = X_Limbs - P255_WIDTH;
+        /* Helper references for top part of X */
+        mbedtls_mpi_uint * const A1 = X + P255_WIDTH;
+        const size_t A1_limbs = X_Limbs - P255_WIDTH;
 
-        /* N = A0 + 38 * A1, capture carry out */
-        carry[0] = mbedtls_mpi_core_mla(X, P255_WIDTH, NT_p, NT_n, 38);
+        /* X = A0 + 38 * A1, capture carry out */
+        carry[0] = mbedtls_mpi_core_mla(X, P255_WIDTH, A1, A1_limbs, 38);
         /* Clear top part */
-        memset(NT_p, 0, sizeof(mbedtls_mpi_uint) * NT_n);
+        memset(A1, 0, sizeof(mbedtls_mpi_uint) * A1_limbs);
     }
 
     /* Step 2: Reduce to <p
      * Split as A0 + 2^255*c, with c a scalar, and compute A0 + 19*c */
     carry[0] <<= 1;
-    carry[0] += (X[P255_WIDTH-1] >> (biL - 1));
+    carry[0] += (X[P255_WIDTH - 1] >> (biL - 1));
     carry[0] *= 19;
 
     /* Clear top bit */
-    X[P255_WIDTH-1] <<= 1; X[P255_WIDTH-1] >>= 1;
+    X[P255_WIDTH - 1] <<= 1; X[P255_WIDTH - 1] >>= 1;
     (void) mbedtls_mpi_core_add(X, X, &carry[0], P255_WIDTH);
 
     return 0;
diff --git a/scripts/mbedtls_dev/ecp.py b/scripts/mbedtls_dev/ecp.py
index 7626eda40..02db438a7 100644
--- a/scripts/mbedtls_dev/ecp.py
+++ b/scripts/mbedtls_dev/ecp.py
@@ -728,53 +728,39 @@ class EcpP255Raw(bignum_common.ModOperationCommon,
         "0", "1",
 
         # Modulus - 1
-        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
-         "ffffffec"),
+        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffec"),
 
         # Modulus + 1
-        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
-         "ffffffee"),
+        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffee"),
 
         # 2^255 - 1
-        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
-         "ffffffff"),
+        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"),
 
         # Maximum canonical P255 multiplication result
-        ("3fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
-         "ffffffec000000000000000000000000000000000000000000000000"
-         "0000000000000190"),
+        ("3fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffec"
+         "0000000000000000000000000000000000000000000000000000000000000190"),
 
         # First 8 number generated by random.getrandbits(510) - seed(2,2)
-        ("1019f0d64ee207f8da94e3e8ab73738fcf1822ffbc6887782b491044d5"
-         "e341245c6e433715ba2bdd177219d30e7a269fd95bafc8f2a4d27bdcf4"
-         "bb99f4bea973"),
-        ("20948fa1feac7eb7dc38f519b91751dacdbd47d364be8049a372db8f6e"
-         "405d93ffed9235288bc781ae66267594c9c9500925e4749b575bd13653"
-         "f8dd9b1f282e"),
-        ("3a1893ea5186ee32ee8d7ee9770348a05d300cb90706a045defc044a09"
-         "325626e6b58de744ab6cce80877b6f71e1f6d2ef8acd128b4f2fc15f3f"
-         "57ebf30b94fa"),
-        ("20a6923522fe99a22c70501e533c91352d3d854e061b90303b08c6e33c"
-         "7295782d6c797f8f7d9b782a1be9cd8697bbd0e2520e33e44c50556c71"
-         "c4a66148a86f"),
-        ("3a248138e8168561867e5e15bc01bfce6a27e0dfcbf8754472154e76e4"
-         "c11ab2fec3f6b32e8d4b8a8f54f8ceacaab39e83844b40ffa9b9f15c14"
-         "bc4a829e07b0"),
-        ("2f450feab714210c665d7435c1066932f4767f26294365b2721dea3bf6"
-         "3f23d0dbe53fcafb2147df5ca495fa5a91c89b97eeab64ca2ce6bc5d3f"
-         "d983c34c769f"),
-        ("1d199effe202849da9643a295a9ac6decbd4d3e2d4dec9ef83f0be4e80"
-         "371eb97f81375eecc1cb6347733e847d718d733ff98ff387c56473a7a8"
-         "3ee0761ebfd2"),
-        ("3423c6ec531d6460f0caeef038c89b38a8acb5137c9260dc74e088a9b9"
-         "492f258ebdbfe3eb9ac688b9d39cca91551e8259cc60b17604e4b4e736"
-         "95c3e652c71a"),
+        ("1019f0d64ee207f8da94e3e8ab73738fcf1822ffbc6887782b491044d5e34124"
+         "5c6e433715ba2bdd177219d30e7a269fd95bafc8f2a4d27bdcf4bb99f4bea973"),
+        ("20948fa1feac7eb7dc38f519b91751dacdbd47d364be8049a372db8f6e405d93"
+         "ffed9235288bc781ae66267594c9c9500925e4749b575bd13653f8dd9b1f282e"),
+        ("3a1893ea5186ee32ee8d7ee9770348a05d300cb90706a045defc044a09325626"
+         "e6b58de744ab6cce80877b6f71e1f6d2ef8acd128b4f2fc15f3f57ebf30b94fa"),
+        ("20a6923522fe99a22c70501e533c91352d3d854e061b90303b08c6e33c729578"
+         "2d6c797f8f7d9b782a1be9cd8697bbd0e2520e33e44c50556c71c4a66148a86f"),
+        ("3a248138e8168561867e5e15bc01bfce6a27e0dfcbf8754472154e76e4c11ab2"
+         "fec3f6b32e8d4b8a8f54f8ceacaab39e83844b40ffa9b9f15c14bc4a829e07b0"),
+        ("2f450feab714210c665d7435c1066932f4767f26294365b2721dea3bf63f23d0"
+         "dbe53fcafb2147df5ca495fa5a91c89b97eeab64ca2ce6bc5d3fd983c34c769f"),
+        ("1d199effe202849da9643a295a9ac6decbd4d3e2d4dec9ef83f0be4e80371eb9"
+         "7f81375eecc1cb6347733e847d718d733ff98ff387c56473a7a83ee0761ebfd2"),
+        ("3423c6ec531d6460f0caeef038c89b38a8acb5137c9260dc74e088a9b9492f25"
+         "8ebdbfe3eb9ac688b9d39cca91551e8259cc60b17604e4b4e73695c3e652c71a"),
 
         # Next 2 number generated by random.getrandbits(255)
-        ("62f1243644a4a8f69dc8db48e86ec9c6e06f291b2a838af8d5c44a4eb3"
-         "172062"),
-        ("6a606e54b4c9e755cc9c3adcf515a8234da4daeb4f3f87777ad1f45ae9"
-         "500ec9"),
+        ("62f1243644a4a8f69dc8db48e86ec9c6e06f291b2a838af8d5c44a4eb3172062"),
+        ("6a606e54b4c9e755cc9c3adcf515a8234da4daeb4f3f87777ad1f45ae9500ec9"),
     ]
 
     @property