diff --git a/zmath.h b/zmath.h
index 76c1212..881abe7 100644
--- a/zmath.h
+++ b/zmath.h
@@ -583,7 +583,7 @@ E_FUNC void zredcpower(REDC *rp, ZVALUE z1, ZVALUE z2, ZVALUE *res);
 #define MODE_MAX	8
 #define MODE2_OFF	(MODE_MAX+1)
 
-#define MODE_INITIAL	MODE_REAL
+#define MODE_INITIAL	MODE_REAL_AUTO
 #define MODE2_INITIAL	MODE2_OFF