diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 8549050..0241b43 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2455,7 +2455,7 @@
 
     ret = pk_decrypt( ssl_own_key( ssl ), p, len,
                       pms, &ssl->handshake->pmslen,
-                      sizeof(ssl->handshake->premaster),
+                      sizeof( ssl->handshake->premaster ) - pms_offset,
                       ssl->f_rng, ssl->p_rng );
 
     if( ret != 0 || ssl->handshake->pmslen != 48 ||