diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 2668a05..bffbef2 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -705,9 +705,9 @@
 
     mbedtls_ssl_ciphersuite_t const *ciphersuite_info;
 
-    void (*update_checksum)(mbedtls_ssl_context *, const unsigned char *, size_t);
-    void (*calc_verify)(const mbedtls_ssl_context *, unsigned char *, size_t *);
-    void (*calc_finished)(mbedtls_ssl_context *, unsigned char *, int);
+    int (*update_checksum)(mbedtls_ssl_context *, const unsigned char *, size_t);
+    int (*calc_verify)(const mbedtls_ssl_context *, unsigned char *, size_t *);
+    int (*calc_finished)(mbedtls_ssl_context *, unsigned char *, int);
     mbedtls_ssl_tls_prf_cb *tls_prf;
 
     /*
@@ -1317,7 +1317,7 @@
 MBEDTLS_CHECK_RETURN_CRITICAL
 int mbedtls_ssl_send_fatal_handshake_failure(mbedtls_ssl_context *ssl);
 
-void mbedtls_ssl_reset_checksum(mbedtls_ssl_context *ssl);
+int mbedtls_ssl_reset_checksum(mbedtls_ssl_context *ssl);
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
 MBEDTLS_CHECK_RETURN_CRITICAL