diff --git a/tf-psa-crypto/drivers/builtin/src/aes.c b/tf-psa-crypto/drivers/builtin/src/aes.c
index 085fd4d..67fa2d5 100644
--- a/tf-psa-crypto/drivers/builtin/src/aes.c
+++ b/tf-psa-crypto/drivers/builtin/src/aes.c
@@ -1925,8 +1925,9 @@
 
             /*
              * AES-192 is an optional feature that may be unavailable when
-             * there is an alternative underlying implementation such as a
-             * PSA driver.
+             * there is an alternative underlying implementation i.e when
+             * MBEDTLS_AES_SETKEY_ENC_ALT or MBEDTLS_AES_SETKEY_DEC_ALT
+             * are defined.
              */
             if (ret == MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED && keybits == 192) {
                 mbedtls_printf("skipped\n");
@@ -1992,8 +1993,9 @@
             ret = mbedtls_aes_setkey_enc(&ctx, key, keybits);
             /*
              * AES-192 is an optional feature that may be unavailable when
-             * there is an alternative underlying implementation such as a
-             * PSA driver.
+             * there is an alternative underlying implementation i.e when
+             * MBEDTLS_AES_SETKEY_ENC_ALT or MBEDTLS_AES_SETKEY_DEC_ALT
+             * are defined.
              */
             if (ret == MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED && keybits == 192) {
                 mbedtls_printf("skipped\n");
@@ -2056,8 +2058,9 @@
             ret = mbedtls_aes_setkey_enc(&ctx, key, keybits);
             /*
              * AES-192 is an optional feature that may be unavailable when
-             * there is an alternative underlying implementation such as a
-             * PSA driver.
+             * there is an alternative underlying implementation i.e when
+             * MBEDTLS_AES_SETKEY_ENC_ALT or MBEDTLS_AES_SETKEY_DEC_ALT
+             * are defined.
              */
             if (ret == MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED && keybits == 192) {
                 mbedtls_printf("skipped\n");