diff --git a/www/whiteboard/export.js b/www/whiteboard/export.js
index 300085c92..7c9253fea 100644
--- a/www/whiteboard/export.js
+++ b/www/whiteboard/export.js
@@ -25,8 +25,9 @@ define([
                     if (c[k].y > h) { h = c[k].y + 1; }
                 });
             });
-            w = Math.min(w, MAX);
-            h = Math.min(h, MAX);
+            // Empty documents are rendered as a 600x600 transparent PNG image
+            w = w === 0 ? 600 : Math.min(w, MAX);
+            h = h === 0 ? 600 : Math.min(h, MAX);
             canvas.setWidth(w);
             canvas.setHeight(h);
             canvas.calcOffset();