diff --git a/features/mbedtls/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F439xI/mbedtls_device.h b/features/mbedtls/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F439xI/mbedtls_device.h
index dfbc82055ef..90213bea118 100644
--- a/features/mbedtls/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F439xI/mbedtls_device.h
+++ b/features/mbedtls/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F439xI/mbedtls_device.h
@@ -20,7 +20,9 @@
 #ifndef MBEDTLS_DEVICE_H
 #define MBEDTLS_DEVICE_H
 
-#define MBEDTLS_AES_ALT
+/* FIXME: Don't enable AES hardware acceleration until issue #4928 is fixed.
+ * (https://github.com/ARMmbed/mbed-os/issues/4928) */
+/* #define MBEDTLS_AES_ALT */
 
 #define MBEDTLS_SHA256_ALT