diff --git a/features/mbedtls/targets/TARGET_STM/sha256_alt.c b/features/mbedtls/targets/TARGET_STM/sha256_alt.c
index a9cf9fbccf..100d21c6f2 100644
--- a/features/mbedtls/targets/TARGET_STM/sha256_alt.c
+++ b/features/mbedtls/targets/TARGET_STM/sha256_alt.c
@@ -71,12 +71,12 @@ void mbedtls_sha256_starts( mbedtls_sha256_context *ctx, int is224 )
     }
 }
 
-void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[64] )
+void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[MBEDTLS_SHA256_BLOCK_SIZE] )
 {
     if (ctx->is224 == 0) {
-        HAL_HASHEx_SHA256_Accumulate(&ctx->hhash_sha256, (uint8_t *) data, 64);
+        HAL_HASHEx_SHA256_Accumulate(&ctx->hhash_sha256, (uint8_t *) data, MBEDTLS_SHA256_BLOCK_SIZE);
     } else {
-        HAL_HASHEx_SHA224_Accumulate(&ctx->hhash_sha256, (uint8_t *) data, 64);
+        HAL_HASHEx_SHA224_Accumulate(&ctx->hhash_sha256, (uint8_t *) data, MBEDTLS_SHA256_BLOCK_SIZE);
     }
 }
 
diff --git a/features/mbedtls/targets/TARGET_STM/sha256_alt.h b/features/mbedtls/targets/TARGET_STM/sha256_alt.h
index b6b6ae1b53..46a9cdd231 100644
--- a/features/mbedtls/targets/TARGET_STM/sha256_alt.h
+++ b/features/mbedtls/targets/TARGET_STM/sha256_alt.h
@@ -98,7 +98,7 @@ void mbedtls_sha256_update( mbedtls_sha256_context *ctx, const unsigned char *in
 void mbedtls_sha256_finish( mbedtls_sha256_context *ctx, unsigned char output[32] );
 
 /* Internal use */
-void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[64] );
+void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[MBEDTLS_SHA256_BLOCK_SIZE] );
 
 #ifdef __cplusplus
 }