1 files changed, 7 insertions, 5 deletions
diff --git a/metapost/context/base/mpiv/mp-tool.mpiv b/metapost/context/base/mpiv/mp-tool.mpiv
index f41811413..6c02323c3 100644
--- a/metapost/context/base/mpiv/mp-tool.mpiv
+++ b/metapost/context/base/mpiv/mp-tool.mpiv
@@ -3754,13 +3754,15 @@ numeric mfun_dash_on, mfun_dash_off ;
 
 primarydef p withdashes len =
     hide (
-        save l, t, n, m ; pair t ;
+        save l, t, n, m, don, doff; pair t ;
         l := arclength p ;
-        t := paired(len) ;
+        t := paired (len) ;
         m := xpart t + ypart t ;
-        n := l / (l div m) / m ;
-        mfun_dash_on  := n * xpart t ;
-        mfun_dash_off := n * ypart t ;
+        n := (l if not cycle p : - xpart t fi) div m ;
+        (n if not cycle p : + 1 fi) * don + n * doff = l ;
+        don*(ypart t) = doff*(xpart t) ;
+        mfun_dash_on := don ;
+        mfun_dash_off := doff ;
     )
     p dashed dashpattern (on mfun_dash_on off mfun_dash_off)
 enddef ;