diff --git a/third_party/NordicSemiconductor/libraries/crypto/nrf52811-mbedtls-config.h b/third_party/NordicSemiconductor/libraries/crypto/nrf52811-mbedtls-config.h
index 87b7b6be8..46f15fecf 100644
--- a/third_party/NordicSemiconductor/libraries/crypto/nrf52811-mbedtls-config.h
+++ b/third_party/NordicSemiconductor/libraries/crypto/nrf52811-mbedtls-config.h
@@ -26,6 +26,9 @@
  *  POSSIBILITY OF SUCH DAMAGE.
  */
 
+#ifndef NRF52811_MBEDTLS_CONFIG_H_
+#define NRF52811_MBEDTLS_CONFIG_H_
+
 #if defined(__ICCARM__)
     _Pragma("diag_suppress=Pe550")
 #endif
@@ -34,3 +37,5 @@
     _Pragma("diag_suppress=550")
     _Pragma("diag_suppress=68")
 #endif
+
+#endif // NRF52811_MBEDTLS_CONFIG_H_
diff --git a/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h b/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
index 490badb1a..92a0a3e22 100644
--- a/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
+++ b/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
@@ -26,6 +26,9 @@
  *  POSSIBILITY OF SUCH DAMAGE.
  */
 
+#ifndef NRF52840_MBEDTLS_CONFIG_H_
+#define NRF52840_MBEDTLS_CONFIG_H_
+
 #ifndef DISABLE_CC310
 #define MBEDTLS_AES_ALT
 #define MBEDTLS_ECP_ALT
@@ -45,3 +48,5 @@
     _Pragma("diag_suppress=550")
     _Pragma("diag_suppress=68")
 #endif
+
+#endif // NRF52840_MBEDTLS_CONFIG_H_