diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 36c96f2..a4d9880 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -8397,7 +8397,7 @@
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
         size_t block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type);
 #else
-        size_t block_size = cipher_info->block_size;
+        size_t block_size = mbedtls_cipher_info_get_block_size(cipher_info);
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)