diff --git a/tgcrypto/tgcrypto.c b/tgcrypto/tgcrypto.c
index 260c17d..997ab6c 100644
--- a/tgcrypto/tgcrypto.c
+++ b/tgcrypto/tgcrypto.c
@@ -16,6 +16,7 @@
 // You should have received a copy of the GNU Lesser General Public License
 // along with Pyrogram.  If not, see <http://www.gnu.org/licenses/>.
 
+#define PY_SSIZE_T_CLEAN
 #include <Python.h>
 
 #include "aes256.h"