diff --git a/src/traces/contour/close_boundaries.js b/src/traces/contour/close_boundaries.js
index 60086f8966c..b1fc71dbedc 100644
--- a/src/traces/contour/close_boundaries.js
+++ b/src/traces/contour/close_boundaries.js
@@ -23,7 +23,8 @@ module.exports = function(pathinfo, contours) {
 
             for(i = 0; i < pathinfo.length; i++) {
                 var pi = pathinfo[i];
-                pi.prefixBoundary = !pi.edgepaths.length && edgeVal2 > pi.level;
+                pi.prefixBoundary = !pi.edgepaths.length &&
+                    (edgeVal2 > pi.level || pi.starts.length && edgeVal2 === pi.level);
             }
             break;
         case 'constraint':
diff --git a/src/traces/contourcarpet/plot.js b/src/traces/contourcarpet/plot.js
index 46d5ece2a6d..72b93ead062 100644
--- a/src/traces/contourcarpet/plot.js
+++ b/src/traces/contourcarpet/plot.js
@@ -330,10 +330,7 @@ function makeFills(trace, plotgroup, xa, ya, pathinfo, perimeter, ab2p, carpet,
     var hasFills = coloring === 'fill';
 
     // fills prefixBoundary in pathinfo items
-    //
-    // N.B. cheater_contour mock fails if we call closeBoundaries
-    //      on contourcarpet traces that with `levels` contours
-    if(hasFills && trace.contours.type === 'constraint') {
+    if(hasFills) {
         closeBoundaries(pathinfo, trace.contours);
     }