diff --git a/selfdrive/mapd/mapd_helpers.py b/selfdrive/mapd/mapd_helpers.py
index f363810b904652..82364dde75cc67 100644
--- a/selfdrive/mapd/mapd_helpers.py
+++ b/selfdrive/mapd/mapd_helpers.py
@@ -253,7 +253,7 @@ def max_speed_ahead(self, current_speed_limit, lat, lon, heading, lookahead):
             a = 111132.954*math.cos(float(latmax+latmin)/360*3.141592)*float(lonmax-lonmin)
           else:
             circle = circle_through_points([way.way.nodes[0].lat,way.way.nodes[0].lon,1], [way.way.nodes[1].lat,way.way.nodes[1].lon,1], [way.way.nodes[-1].lat,way.way.nodes[-1].lon,1])
-            a = 111132.954*math.cos(float(latmax+latmin)/360*3.141592)*float(circle[2])
+            a = 111132.954*math.cos(float(latmax+latmin)/360*3.141592)*float(circle[2])*2
           speed_ahead = np.sqrt(1.6075*a)
           min_dist = 999.9
           for w in way_pts: