diff --git a/mpz/fac_ui.c b/mpz/fac_ui.c
index 55642bc3..c9d02d40 100644
--- a/mpz/fac_ui.c
+++ b/mpz/fac_ui.c
@@ -24,8 +24,9 @@ MA 02110-1301, USA. */
 #include "gmp-impl.h"
 #include "longlong.h"
 
+#ifndef MPZ_FAC_IS_TUNING
 #include "fac_ui.h"
-
+#endif
 
 static void odd_product _PROTO ((unsigned long low, unsigned long high, mpz_t * st));
 static void ap_product_small _PROTO ((mpz_t ret, mp_limb_t start, mp_limb_t step, unsigned long count, unsigned long nm));
diff --git a/tune/fac_ui_large.c b/tune/fac_ui_large.c
index ae09804a..26dba671 100644
--- a/tune/fac_ui_large.c
+++ b/tune/fac_ui_large.c
@@ -28,4 +28,6 @@ MA 02110-1301, USA.
 #define FAC_UI_THRESHOLD  1
 #define __gmpz_fac_ui  mpz_fac_ui_large
 
+#define MPZ_FAC_IS_TUNING
+#include "../mpz/fac_ui.h"
 #include "../mpz/fac_ui.c"
diff --git a/tune/fac_ui_small.c b/tune/fac_ui_small.c
index 33b2cdc3..e0161bbe 100644
--- a/tune/fac_ui_small.c
+++ b/tune/fac_ui_small.c
@@ -28,4 +28,6 @@ MA 02110-1301, USA.
 #define FAC_UI_THRESHOLD    MP_SIZE_T_MAX
 #define __gmpz_fac_ui  mpz_fac_ui_small
 
+#define MPZ_FAC_IS_TUNING
+#include "../mpz/fac_ui.h"
 #include "../mpz/fac_ui.c"