diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index afbcdd9..1c44b7d 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -5598,9 +5598,9 @@
 
 void mbedtls_ssl_set_bio( mbedtls_ssl_context *ssl,
         void *p_bio,
-        int (*f_send)(void *, const unsigned char *, size_t),
-        int (*f_recv)(void *, unsigned char *, size_t),
-        int (*f_recv_timeout)(void *, unsigned char *, size_t, uint32_t) )
+        mbedtls_ssl_send_t *f_send,
+        mbedtls_ssl_recv_t *f_recv,
+        mbedtls_ssl_recv_timeout_t *f_recv_timeout )
 {
     ssl->p_bio          = p_bio;
     ssl->f_send         = f_send;
@@ -5615,8 +5615,8 @@
 
 void mbedtls_ssl_set_timer_cb( mbedtls_ssl_context *ssl,
                                void *p_timer,
-                               void (*f_set_timer)(void *, uint32_t int_ms, uint32_t fin_ms),
-                               int (*f_get_timer)(void *) )
+                               mbedtls_ssl_set_timer_t *f_set_timer,
+                               mbedtls_ssl_get_timer_t *f_get_timer )
 {
     ssl->p_timer        = p_timer;
     ssl->f_set_timer    = f_set_timer;