diff --git a/src/jscanify-node.js b/src/jscanify-node.js
index 3d7ec2d..6779fb1 100644
--- a/src/jscanify-node.js
+++ b/src/jscanify-node.js
@@ -80,7 +80,10 @@ class jscanify {
       }
     }
 
-    const maxContour = contours.get(maxContourIndex);
+    const maxContour =
+    maxContourIndex >= 0 ?
+      contours.get(maxContourIndex) :
+      null;
 
     imgGray.delete();
     imgBlur.delete();