diff --git a/include/mbedtls/psa_util.h b/include/mbedtls/psa_util.h
index a2604e1f3..cfb4bce58 100644
--- a/include/mbedtls/psa_util.h
+++ b/include/mbedtls/psa_util.h
@@ -126,16 +126,11 @@ psa_ecc_family_t mbedtls_ecc_group_to_psa(mbedtls_ecp_group_id grpid,
  * \param curve         A PSA elliptic curve identifier
  *                      (`PSA_ECC_FAMILY_xxx`).
  * \param bits          The bit-length of a private key on \p curve.
- * \param bits_is_sloppy If true, \p bits may be the bit-length rounded up
- *                      to the nearest multiple of 8. This allows the caller
- *                      to infer the exact curve from the length of a key
- *                      which is supplied as a byte string.
  *
  * \return              The corresponding Mbed TLS elliptic curve identifier
  *                      (`MBEDTLS_ECP_DP_xxx`).
- * \return              #MBEDTLS_ECP_DP_NONE if \c curve is not recognized.
- * \return              #MBEDTLS_ECP_DP_NONE if \p bits is not
- *                      correct for \p curve.
+ * \return              #MBEDTLS_ECP_DP_NONE if the combination of \c curve
+ *                      and \p bits is not recognized.
  */
 mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t curve,
                                                 size_t bits);
diff --git a/library/psa_crypto_ecp.c b/library/psa_crypto_ecp.c
index 866ef7956..3c5aa729b 100644
--- a/library/psa_crypto_ecp.c
+++ b/library/psa_crypto_ecp.c
@@ -32,13 +32,16 @@
     defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) || \
     defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA) || \
     defined(MBEDTLS_PSA_BUILTIN_ALG_ECDH)
-/* Helper function to verify if the provided EC's family and key bit size are
- * valid. */
-static int check_ecc_parameters(psa_ecc_family_t family, size_t bits, int allow_bit_size_roundup)
+/* Helper function to verify if the provided EC's family and key bit size are valid.
+ *
+ * Note: "bits" parameter is used both as input and output and it might be updated
+ *       in case provided input value is not multiple of 8 ("sloppy" bits).
+ */
+static int check_ecc_parameters(psa_ecc_family_t family, size_t *bits)
 {
     switch (family) {
         case PSA_ECC_FAMILY_SECP_R1:
-            switch (bits) {
+            switch (*bits) {
                 case 192:
                 case 224:
                 case 256:
@@ -46,14 +49,13 @@ static int check_ecc_parameters(psa_ecc_family_t family, size_t bits, int allow_
                 case 521:
                     return PSA_SUCCESS;
                 case 528:
-                    if (allow_bit_size_roundup) {
-                        return PSA_SUCCESS;
-                    }
+                    *bits = 521;
+                    return PSA_SUCCESS;
             }
             break;
 
         case PSA_ECC_FAMILY_BRAINPOOL_P_R1:
-            switch (bits) {
+            switch (*bits) {
                 case 256:
                 case 384:
                 case 512:
@@ -62,19 +64,18 @@ static int check_ecc_parameters(psa_ecc_family_t family, size_t bits, int allow_
             break;
 
         case PSA_ECC_FAMILY_MONTGOMERY:
-            switch (bits) {
+            switch (*bits) {
                 case 448:
                 case 255:
                     return PSA_SUCCESS;
                 case 256:
-                    if (allow_bit_size_roundup) {
-                        return PSA_SUCCESS;
-                    }
+                    *bits = 255;
+                    return PSA_SUCCESS;
             }
             break;
 
         case PSA_ECC_FAMILY_SECP_K1:
-            switch (bits) {
+            switch (*bits) {
                 case 192:
                 case 224:
                 case 256:
@@ -136,8 +137,7 @@ psa_status_t mbedtls_psa_ecp_load_representation(
     }
     mbedtls_ecp_keypair_init(ecp);
 
-    status = check_ecc_parameters(PSA_KEY_TYPE_ECC_GET_FAMILY(type), curve_bits,
-                                  !explicit_bits);
+    status = check_ecc_parameters(PSA_KEY_TYPE_ECC_GET_FAMILY(type), &curve_bits);
     if (status != PSA_SUCCESS) {
         goto exit;
     }
diff --git a/library/psa_util.c b/library/psa_util.c
index abd7a5f6b..28b028552 100644
--- a/library/psa_util.c
+++ b/library/psa_util.c
@@ -276,7 +276,6 @@ mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t curve,
 #endif
 #if defined(PSA_WANT_ECC_SECP_R1_521)
                 case 521:
-                case 528:
                     return MBEDTLS_ECP_DP_SECP521R1;
 #endif
             }
@@ -303,7 +302,6 @@ mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t curve,
             switch (bits) {
 #if defined(PSA_WANT_ECC_MONTGOMERY_255)
                 case 255:
-                case 256:
                     return MBEDTLS_ECP_DP_CURVE25519;
 #endif
 #if defined(PSA_WANT_ECC_MONTGOMERY_448)