diff --git a/tune/set_strp.c b/tune/set_strp.c
new file mode 100644
index 00000000..53001b3e
--- /dev/null
+++ b/tune/set_strp.c
@@ -0,0 +1,32 @@
+/* mpn_set_str_subquad -- mpn_set_str forced to the sub-quadratic case.
+
+Copyright 2002 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
+
+#define TUNE_PROGRAM_BUILD  1   /* for gmp-impl.h */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+void
+mpn_pre_set_str (mp_ptr wp, unsigned char *str, size_t str_len, powers_t *powtab, mp_ptr tp)
+{
+  if (BELOW_THRESHOLD (str_len, set_str_dc_threshold))
+    mpn_bc_set_str (wp, str, str_len, powtab->base);
+  else
+    mpn_dc_set_str (wp, str, str_len, powtab, tp);
+}