diff --git a/collisiontest.p8 b/collisiontest.p8
index 16b5691..487dc15 100644
--- a/collisiontest.p8
+++ b/collisiontest.p8
@@ -187,7 +187,7 @@ function linefill(ax,ay,bx,by,r,c)
  local d,n = abs(dx),abs(dy)
  if (d<n) d,n=n,d
  n/=d
- d*=(n*n+1)^0.5
+ d*=sqrt(n*n+1)
  if(d<0.001) return
  local ca,sa=dx/d,-dy/d