diff --git a/src/mode/fdm/prepare.js b/src/mode/fdm/prepare.js
index be1c7c07..8db5507c 100644
--- a/src/mode/fdm/prepare.js
+++ b/src/mode/fdm/prepare.js
@@ -68,7 +68,7 @@
                 offset = process.outputBrimOffset || (process.outputRaft ? 4 : 0);
 
             // compute first brim
-            widgets.forEach(function(widget) {
+            widgets.filter(w => w.slices.length).forEach(function(widget) {
                 let tops = [];
                 // collect top outer polygons
                 widget.slices[0].tops.forEach(function(top) {