diff --git a/chameleonic.p8 b/chameleonic.p8
index 7bdd8c1..d250974 100644
--- a/chameleonic.p8
+++ b/chameleonic.p8
@@ -416,8 +416,9 @@ end
 function level:recollide_reanchor()
  self._coll={}
  for mx=0,15 do
+  local kmx=mx..","
   for my=0,15 do
-   local mxy=_mix{mx,my}
+   local mxy=kmx..my
    self._coll[mxy]=
     fget(self:_mget(mx,my),7) or
     self._crates[mxy]
@@ -430,18 +431,19 @@ function level:recollide_reanchor()
  -1`1
  1`1]]) do
   local dx,dy=unpack(dxy)
-  assert(dx!=0 and dy!=0)
+  local c=self._coll
   for mx0=0,15 do
+   local mx1=mx0+dx
+   local kmx0,kmx1=mx0..",",mx1..","
    for my0=0,15 do
-    local mx1,my1=mx0+dx,my0+dy
+    local my1=my0+dy
 
     -- bypass mcoll for MEGA SPEED
-    local c=self._coll
     if (
-     c[mx0..","..my0] and not self:get_crate(mx0,my0) and
-     not c[mx0..","..my1] and
-     not c[mx1..","..my0] and
-     not c[mx1..","..my1]
+     c[kmx0..my0] and not self:get_crate(mx0,my0) and
+     not c[kmx0..my1] and
+     not c[kmx1..my0] and
+     not c[kmx1..my1]
     ) then
      local key=_mix{"GEOM",mx0,my0,dx,dy}
      anch_new[key]= {