diff --git a/include/mbedtls/block_cipher.h b/include/mbedtls/block_cipher.h
index 535412a857..2286a57812 100644
--- a/include/mbedtls/block_cipher.h
+++ b/include/mbedtls/block_cipher.h
@@ -52,9 +52,9 @@ typedef enum {
 typedef struct {
     mbedtls_block_cipher_id_t MBEDTLS_PRIVATE(id);
 #if defined(MBEDTLS_BLOCK_CIPHER_SOME_PSA)
-    mbedtls_block_cipher_engine_t engine;
-    psa_key_type_t psa_key_type;
-    mbedtls_svc_key_id_t psa_key_id;
+    mbedtls_block_cipher_engine_t MBEDTLS_PRIVATE(engine);
+    psa_key_type_t MBEDTLS_PRIVATE(psa_key_type);
+    mbedtls_svc_key_id_t MBEDTLS_PRIVATE(psa_key_id);
 #endif
     union {
         unsigned dummy; /* Make the union non-empty even with no supported algorithms. */