diff --git a/drivers/auth/mbedtls/mbedtls_crypto.mk b/drivers/auth/mbedtls/mbedtls_crypto.mk
index 11df5ad..cb81d4d 100644
--- a/drivers/auth/mbedtls/mbedtls_crypto.mk
+++ b/drivers/auth/mbedtls/mbedtls_crypto.mk
@@ -6,10 +6,20 @@
 
 include drivers/auth/mbedtls/mbedtls_common.mk
 
-# The platform may define the variable 'MBEDTLS_KEY_ALG' to select the key
+# The platform may define the variable 'TF_MBEDTLS_KEY_ALG' to select the key
 # algorithm to use. Default algorithm is RSA.
-ifeq (${MBEDTLS_KEY_ALG},)
-    MBEDTLS_KEY_ALG		:=	rsa
+ifeq (${TF_MBEDTLS_KEY_ALG},)
+    TF_MBEDTLS_KEY_ALG		:=	rsa
+endif
+
+# If MBEDTLS_KEY_ALG build flag is defined use it to set TF_MBEDTLS_KEY_ALG for
+# backward compatibility
+ifdef MBEDTLS_KEY_ALG
+    ifeq (${ERROR_DEPRECATED},1)
+        $(error "MBEDTLS_KEY_ALG is deprecated. Please use the new build flag TF_MBEDTLS_KEY_ALG")
+    endif
+    $(warning "MBEDTLS_KEY_ALG is deprecated. Please use the new build flag TF_MBEDTLS_KEY_ALG")
+    TF_MBEDTLS_KEY_ALG	:= ${MBEDTLS_KEY_ALG}
 endif
 
 MBEDTLS_CRYPTO_SOURCES		:=	drivers/auth/mbedtls/mbedtls_crypto.c	\
@@ -25,20 +35,20 @@
 					)
 
 # Key algorithm specific files
-ifeq (${MBEDTLS_KEY_ALG},ecdsa)
+ifeq (${TF_MBEDTLS_KEY_ALG},ecdsa)
     MBEDTLS_CRYPTO_SOURCES	+=	$(addprefix ${MBEDTLS_DIR}/library/,	\
     					ecdsa.c					\
     					ecp_curves.c				\
     					ecp.c					\
     					)
     TF_MBEDTLS_KEY_ALG_ID	:=	TF_MBEDTLS_ECDSA
-else ifeq (${MBEDTLS_KEY_ALG},rsa)
+else ifeq (${TF_MBEDTLS_KEY_ALG},rsa)
     MBEDTLS_CRYPTO_SOURCES	+=	$(addprefix ${MBEDTLS_DIR}/library/,	\
     					rsa.c					\
     					)
     TF_MBEDTLS_KEY_ALG_ID	:=	TF_MBEDTLS_RSA
 else
-    $(error "MBEDTLS_KEY_ALG=${MBEDTLS_KEY_ALG} not supported on mbed TLS")
+    $(error "TF_MBEDTLS_KEY_ALG=${TF_MBEDTLS_KEY_ALG} not supported on mbed TLS")
 endif
 
 # Needs to be set to drive mbed TLS configuration correctly