diff --git a/programs/pkey/dh_server.c b/programs/pkey/dh_server.c
index 9d51c14..e469bbc 100644
--- a/programs/pkey/dh_server.c
+++ b/programs/pkey/dh_server.c
@@ -229,7 +229,7 @@
     buf[n + 1] = (unsigned char)( rsa.MBEDTLS_PRIVATE(len)      );
 
     if( ( ret = mbedtls_rsa_pkcs1_sign( &rsa, NULL, NULL, MBEDTLS_MD_SHA256,
-                                0, hash, buf + n + 2 ) ) != 0 )
+                                32, hash, buf + n + 2 ) ) != 0 )
     {
         mbedtls_printf( " failed\n  ! mbedtls_rsa_pkcs1_sign returned %d\n\n", ret );
         goto exit;