diff --git a/space.h b/space.h
index 7fbd13781fbf2805192663117dd8e985ab2b8c65..04cc09b9522c1f2d121ddef5c122303830717d71 100644
--- a/space.h
+++ b/space.h
@@ -25,7 +25,7 @@
 #define space_cellallocchunk            1000
 #define space_splitratio                0.875
 #define space_splitsize_default         800
-#define space_dosub                     0
+#define space_dosub                     1
 #define task_maxwait                    3
 #define task_maxunlock                  39