diff --git a/include/mbedtls/bignum.h b/include/mbedtls/bignum.h
index eb372cf..2a50b40 100644
--- a/include/mbedtls/bignum.h
+++ b/include/mbedtls/bignum.h
@@ -129,6 +129,7 @@
         #endif /* !MBEDTLS_HAVE_INT64 */
 typedef  int64_t mbedtls_mpi_sint;
 typedef uint64_t mbedtls_mpi_uint;
+#define MBEDTLS_MPI_UINT_MAX                UINT64_MAX
     #elif defined(__GNUC__) && (                         \
     defined(__amd64__) || defined(__x86_64__)     || \
     defined(__ppc64__) || defined(__powerpc64__)  || \
@@ -141,6 +142,7 @@
         #endif /* MBEDTLS_HAVE_INT64 */
 typedef  int64_t mbedtls_mpi_sint;
 typedef uint64_t mbedtls_mpi_uint;
+#define MBEDTLS_MPI_UINT_MAX                UINT64_MAX
         #if !defined(MBEDTLS_NO_UDBL_DIVISION)
 /* mbedtls_t_udbl defined as 128-bit unsigned int */
 typedef unsigned int mbedtls_t_udbl __attribute__((mode(TI)));
@@ -156,6 +158,7 @@
         #endif /* !MBEDTLS_HAVE_INT64 */
 typedef  int64_t mbedtls_mpi_sint;
 typedef uint64_t mbedtls_mpi_uint;
+#define MBEDTLS_MPI_UINT_MAX                UINT64_MAX
         #if !defined(MBEDTLS_NO_UDBL_DIVISION)
 /* mbedtls_t_udbl defined as 128-bit unsigned int */
 typedef __uint128_t mbedtls_t_udbl;
@@ -165,6 +168,7 @@
 /* Force 64-bit integers with unknown compiler */
 typedef  int64_t mbedtls_mpi_sint;
 typedef uint64_t mbedtls_mpi_uint;
+#define MBEDTLS_MPI_UINT_MAX                UINT64_MAX
     #endif
 #endif /* !MBEDTLS_HAVE_INT32 */
 
@@ -175,6 +179,7 @@
     #endif /* !MBEDTLS_HAVE_INT32 */
 typedef  int32_t mbedtls_mpi_sint;
 typedef uint32_t mbedtls_mpi_uint;
+#define MBEDTLS_MPI_UINT_MAX                UINT32_MAX
     #if !defined(MBEDTLS_NO_UDBL_DIVISION)
 typedef uint64_t mbedtls_t_udbl;
         #define MBEDTLS_HAVE_UDBL
diff --git a/library/bignum.c b/library/bignum.c
index 5b92932..d559c9e 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -900,6 +900,8 @@
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t j;
+    mbedtls_mpi_uint *p;
+    mbedtls_mpi_uint c;
     MPI_VALIDATE_RET(X != NULL);
     MPI_VALIDATE_RET(A != NULL);
     MPI_VALIDATE_RET(B != NULL);
@@ -933,9 +935,9 @@
 
     /* j is the number of non-zero limbs of B. Add those to X. */
 
-    mbedtls_mpi_uint *p = X->p;
+    p = X->p;
 
-    mbedtls_mpi_uint c = mbedtls_mpi_core_add(p, p, B->p, j);
+    c = mbedtls_mpi_core_add(p, p, B->p, j);
 
     p += j;
 
diff --git a/library/bignum_core.c b/library/bignum_core.c
index de57cfc..8bf819c 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -36,22 +36,17 @@
 size_t mbedtls_mpi_core_clz(mbedtls_mpi_uint a)
 {
 #if defined(__has_builtin)
-#if __has_builtin(__builtin_clz)
-    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned int)) {
-        return (size_t) __builtin_clz(a);
-    }
-#endif
-#if __has_builtin(__builtin_clzl)
-    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned long)) {
-        return (size_t) __builtin_clzl(a);
-    }
-#endif
-#if __has_builtin(__builtin_clzll)
-    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned long long)) {
-        return (size_t) __builtin_clzll(a);
-    }
+#if (MBEDTLS_MPI_UINT_MAX == UINT_MAX) && __has_builtin(__builtin_clz)
+    #define core_clz __builtin_clz
+#elif (MBEDTLS_MPI_UINT_MAX == ULONG_MAX) && __has_builtin(__builtin_clzl)
+    #define core_clz __builtin_clzl
+#elif (MBEDTLS_MPI_UINT_MAX == ULLONG_MAX) && __has_builtin(__builtin_clzll)
+    #define core_clz __builtin_clzll
 #endif
 #endif
+#if defined(core_clz)
+    return (size_t) core_clz(a);
+#else
     size_t j;
     mbedtls_mpi_uint mask = (mbedtls_mpi_uint) 1 << (biL - 1);
 
@@ -64,6 +59,7 @@
     }
 
     return j;
+#endif
 }
 
 size_t mbedtls_mpi_core_bitlen(const mbedtls_mpi_uint *A, size_t A_limbs)
diff --git a/library/common.h b/library/common.h
index 2d35814..66033dc 100644
--- a/library/common.h
+++ b/library/common.h
@@ -242,8 +242,12 @@
 /* Define `asm` for compilers which don't define it. */
 /* *INDENT-OFF* */
 #ifndef asm
+#if defined(__IAR_SYSTEMS_ICC__)
+#define asm __asm
+#else
 #define asm __asm__
 #endif
+#endif
 /* *INDENT-ON* */
 
 /*
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 3d3ec60..e3b3376 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -5658,6 +5658,7 @@
     size_t shift   = bits % biL;
     size_t adjust  = (shift + biL - 1) / biL;
     size_t P_limbs = bits / biL + adjust;
+    mbedtls_mpi_uint mask = 0;
 
     mbedtls_mpi_uint *A1 = mbedtls_calloc(P_limbs, ciL);
     if (A1 == NULL) {
@@ -5673,7 +5674,6 @@
         goto cleanup;
     }
 
-    mbedtls_mpi_uint mask = 0;
     if (adjust != 0) {
         mask  = ((mbedtls_mpi_uint) 1 << shift) - 1;
     }
diff --git a/library/platform_util.c b/library/platform_util.c
index c67b80d..2e93a5b 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -97,7 +97,8 @@
  * mbedtls_platform_zeroize() to use a suitable implementation for their
  * platform and needs.
  */
-#if !defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO) && !defined(__STDC_LIB_EXT1__) \
+#if !defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO) && !(defined(__STDC_LIB_EXT1__) && \
+    !defined(__IAR_SYSTEMS_ICC__)) \
     && !defined(_WIN32)
 static void *(*const volatile memset_func)(void *, int, size_t) = memset;
 #endif
@@ -118,7 +119,7 @@
          */
         __msan_unpoison(buf, len);
 #endif
-#elif defined(__STDC_LIB_EXT1__)
+#elif defined(__STDC_LIB_EXT1__) && !defined(__IAR_SYSTEMS_ICC__)
         memset_s(buf, len, 0, len);
 #elif defined(_WIN32)
         SecureZeroMemory(buf, len);
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index a2a6755..5e8d0d0 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1535,6 +1535,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot;
+    psa_key_attributes_t attributes;
 
     /* Reject a zero-length output buffer now, since this can never be a
      * valid key representation. This way we know that data must be a valid
@@ -1560,7 +1561,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
     status = psa_driver_wrapper_export_public_key(
@@ -2509,6 +2510,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot = NULL;
+    psa_key_attributes_t attributes;
 
     /* A context must be freshly initialized before it can be set up. */
     if (operation->id != 0) {
@@ -2525,7 +2527,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -2695,6 +2697,7 @@
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot;
     uint8_t operation_mac_size = 0;
+    psa_key_attributes_t attributes;
 
     status = psa_get_and_lock_key_slot_with_policy(
         key,
@@ -2705,7 +2708,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -2831,6 +2834,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot;
+    psa_key_attributes_t attributes;
 
     *signature_length = 0;
 
@@ -2862,7 +2866,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -3165,6 +3169,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot;
+    psa_key_attributes_t attributes;
 
     (void) input;
     (void) input_length;
@@ -3189,7 +3194,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -3216,6 +3221,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot;
+    psa_key_attributes_t attributes;
 
     (void) input;
     (void) input_length;
@@ -3239,7 +3245,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -3313,6 +3319,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot;
+    psa_key_attributes_t attributes;
 
     /* Check that start has not been previously called, or operation has not
      * previously errored. */
@@ -3339,7 +3346,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -4020,6 +4027,7 @@
     psa_key_usage_t usage = (cipher_operation == MBEDTLS_ENCRYPT ?
                              PSA_KEY_USAGE_ENCRYPT :
                              PSA_KEY_USAGE_DECRYPT);
+    psa_key_attributes_t attributes;
 
     /* A context must be freshly initialized before it can be set up. */
     if (operation->id != 0) {
@@ -4049,7 +4057,7 @@
     }
     operation->default_iv_length = PSA_CIPHER_IV_LENGTH(slot->attr.type, alg);
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -4275,6 +4283,7 @@
     psa_key_slot_t *slot = NULL;
     uint8_t local_iv[PSA_CIPHER_IV_MAX_SIZE];
     size_t default_iv_length = 0;
+    psa_key_attributes_t attributes;
 
     if (!PSA_ALG_IS_CIPHER(alg)) {
         status = PSA_ERROR_INVALID_ARGUMENT;
@@ -4288,7 +4297,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -4345,6 +4354,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot = NULL;
+    psa_key_attributes_t attributes;
 
     if (!PSA_ALG_IS_CIPHER(alg)) {
         status = PSA_ERROR_INVALID_ARGUMENT;
@@ -4358,7 +4368,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -4612,6 +4622,7 @@
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot = NULL;
     psa_key_usage_t key_usage = 0;
+    psa_key_attributes_t attributes;
 
     status = psa_aead_check_algorithm(alg);
     if (status != PSA_SUCCESS) {
@@ -4641,7 +4652,7 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -5789,6 +5800,8 @@
     mbedtls_mpi diff_N_2;
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    size_t m;
+    size_t m_bytes;
 
     mbedtls_mpi_init(&k);
     mbedtls_mpi_init(&diff_N_2);
@@ -5810,9 +5823,9 @@
 
     /* N is the boundary of the private key domain (ecp_group.N). */
     /* Let m be the bit size of N. */
-    size_t m = ecp_group.nbits;
+    m = ecp_group.nbits;
 
-    size_t m_bytes = PSA_BITS_TO_BYTES(m);
+    m_bytes = PSA_BITS_TO_BYTES(m);
 
     /* Calculate N - 2 - it will be needed later. */
     MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&diff_N_2, &ecp_group.N, 2));
@@ -5965,6 +5978,7 @@
     size_t bytes = PSA_BITS_TO_BYTES(bits);
     size_t storage_size = bytes;
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    psa_key_attributes_t attributes;
 
     if (PSA_KEY_TYPE_IS_PUBLIC_KEY(slot->attr.type)) {
         return PSA_ERROR_INVALID_ARGUMENT;
@@ -6013,7 +6027,7 @@
     }
 
     slot->attr.bits = (psa_key_bits_t) bits;
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
@@ -7114,6 +7128,7 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot = NULL;
+    size_t expected_length;
 
     if (!PSA_ALG_IS_KEY_AGREEMENT(alg)) {
         status = PSA_ERROR_INVALID_ARGUMENT;
@@ -7133,7 +7148,7 @@
      * PSA_RAW_KEY_AGREEMENT_OUTPUT_SIZE() is exact so the point is moot.
      * If FFDH is implemented, PSA_RAW_KEY_AGREEMENT_OUTPUT_SIZE() can easily
      * be exact for it as well. */
-    size_t expected_length =
+    expected_length =
         PSA_RAW_KEY_AGREEMENT_OUTPUT_SIZE(slot->attr.type, slot->attr.bits);
     if (output_size < expected_length) {
         status = PSA_ERROR_BUFFER_TOO_SMALL;
@@ -7789,6 +7804,8 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
     psa_key_slot_t *slot = NULL;
+    psa_key_attributes_t attributes;
+    psa_key_type_t type;
 
     if (operation->stage != PSA_PAKE_OPERATION_STAGE_COLLECT_INPUTS) {
         status = PSA_ERROR_BAD_STATE;
@@ -7802,11 +7819,11 @@
         goto exit;
     }
 
-    psa_key_attributes_t attributes = {
+    attributes = (psa_key_attributes_t) {
         .core = slot->attr
     };
 
-    psa_key_type_t type = psa_get_key_type(&attributes);
+    type = psa_get_key_type(&attributes);
 
     if (type != PSA_KEY_TYPE_PASSWORD &&
         type != PSA_KEY_TYPE_PASSWORD_HASH) {
diff --git a/tests/src/test_helpers/ssl_helpers.c b/tests/src/test_helpers/ssl_helpers.c
index 5f203ab..761d877 100644
--- a/tests/src/test_helpers/ssl_helpers.c
+++ b/tests/src/test_helpers/ssl_helpers.c
@@ -930,13 +930,14 @@
                                int *written,
                                const int expected_fragments)
 {
+    int ret;
     /* Verify that calling mbedtls_ssl_write with a NULL buffer and zero length is
      * a valid no-op for TLS connections. */
     if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
         TEST_ASSERT(mbedtls_ssl_write(ssl, NULL, 0) == 0);
     }
 
-    int ret = mbedtls_ssl_write(ssl, buf + *written, buf_len - *written);
+    ret = mbedtls_ssl_write(ssl, buf + *written, buf_len - *written);
     if (ret > 0) {
         *written += ret;
     }
@@ -976,13 +977,14 @@
                               int *read, int *fragments,
                               const int expected_fragments)
 {
+    int ret;
     /* Verify that calling mbedtls_ssl_write with a NULL buffer and zero length is
      * a valid no-op for TLS connections. */
     if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
         TEST_ASSERT(mbedtls_ssl_read(ssl, NULL, 0) == 0);
     }
 
-    int ret = mbedtls_ssl_read(ssl, buf + *read, buf_len - *read);
+    ret = mbedtls_ssl_read(ssl, buf + *read, buf_len - *read);
     if (ret > 0) {
         (*fragments)++;
         *read += ret;