diff --git a/library/platform_util.c b/library/platform_util.c
index c67b80dea..2e93a5b01 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 @@ void mbedtls_platform_zeroize(void *buf, size_t len)
          */
         __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);