diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/aes/aes_alt.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/aes/aes_alt.c
index 6df2663d16..ff59e66237 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/aes/aes_alt.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/aes/aes_alt.c
@@ -21,6 +21,9 @@
  *  http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -588,3 +591,5 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
 
 
 #endif /* MBEDTLS_AES_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt.c
index fb75266a36..3643ffd691 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt.c
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -408,3 +411,5 @@ static int mbedtls_des_docrypt(uint16_t keyopt, uint8_t key[3][MBEDTLS_DES_KEY_S
 
 #endif /* MBEDTLS_DES_ALT */
 #endif /* MBEDTLS_DES_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt_sw.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt_sw.c
index 1e51151c86..59a94d0164 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt_sw.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/des/des_alt_sw.c
@@ -25,6 +25,9 @@
  *  http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -795,3 +798,5 @@ int mbedtls_des3_sw_crypt_cbc( mbedtls_des3_sw_context *ctx,
 
 #endif /* MBEDTLS_DES_ALT */
 #endif /* MBEDTLS_DES_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt.c
index de6ff01415..dfa8cda864 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt.c
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -136,3 +139,5 @@ void mbedtls_sha1_process(mbedtls_sha1_context *ctx, const unsigned char data[64
 
 #endif /* MBEDTLS_SHA1_ALT */
 #endif /* MBEDTLS_SHA1_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt_sw.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt_sw.c
index 230c872465..18b0c496c6 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt_sw.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha1_alt_sw.c
@@ -24,6 +24,9 @@
  *  http://www.itl.nist.gov/fipspubs/fip180-1.htm
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -343,3 +346,5 @@ void mbedtls_sha1_sw_finish( mbedtls_sha1_sw_context *ctx, unsigned char output[
 #endif /* MBEDTLS_SHA1_ALT */
 
 #endif /* MBEDTLS_SHA1_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt.c
index e5fd727e2a..f62f0e2810 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt.c
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -137,3 +140,5 @@ void mbedtls_sha256_process(mbedtls_sha256_context *ctx, const unsigned char dat
 
 #endif /* MBEDTLS_SHA256_ALT */
 #endif /* MBEDTLS_SHA256_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt_sw.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt_sw.c
index 3ac2b61317..a6db9b136b 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt_sw.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha256_alt_sw.c
@@ -24,6 +24,9 @@
  *  http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -317,3 +320,5 @@ void mbedtls_sha256_sw_finish( mbedtls_sha256_sw_context *ctx, unsigned char out
 #endif /* MBEDTLS_SHA256_ALT */
 
 #endif /* MBEDTLS_SHA256_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha_alt_hw.c b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha_alt_hw.c
index 4f26b808d5..2eb7536959 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha_alt_hw.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/crypto/sha/sha_alt_hw.c
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+/* Compatible with mbed OS 2 which doesn't support mbedtls */
+#if MBED_CONF_RTOS_PRESENT
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
@@ -331,3 +334,5 @@ void crypto_sha_getinternstate(unsigned char output[], size_t olen)
 #endif /* MBEDTLS_SHA1_ALT || MBEDTLS_SHA256_ALT || MBEDTLS_SHA512_ALT */
 
 #endif /* MBEDTLS_SHA1_C || MBEDTLS_SHA256_C || MBEDTLS_SHA512_C */
+
+#endif /* MBED_CONF_RTOS_PRESENT */