diff --git a/js/atree.js b/js/atree.js
index 4a9d492..519349b 100644
--- a/js/atree.js
+++ b/js/atree.js
@@ -199,7 +199,6 @@ const atree_node = new (class extends ComputeNode {
 const atree_render = new (class extends ComputeNode {
     constructor() {
         super('builder-atree-render');
-        this.fail_cb = true;
         this.UI_elem = document.getElementById("atree-ui");
         this.list_elem = document.getElementById("atree-header");
     }
diff --git a/js/builder_graph.js b/js/builder_graph.js
index b2ed8cb..0ae6fbd 100644
--- a/js/builder_graph.js
+++ b/js/builder_graph.js
@@ -429,6 +429,7 @@ class PlayerClassNode extends ValueCheckComputeNode {
     compute_func(input_map) {
         if (input_map.size !== 1) { throw "PlayerClassNode accepts exactly one input (build)"; }
         const [build] = input_map.values();  // Extract values, pattern match it into size one list and bind to first element
+        if (build.weapon.statMap.has('NONE')) { return null; }
         return wep_to_class.get(build.weapon.statMap.get('type'));
     }
 }
diff --git a/js/computation_graph.js b/js/computation_graph.js
index d144e29..bd46036 100644
--- a/js/computation_graph.js
+++ b/js/computation_graph.js
@@ -135,7 +135,7 @@ class ComputeNode {
 }
 
 class ValueCheckComputeNode extends ComputeNode {
-    constructor(name) { super(name); }
+    constructor(name) { super(name); this.valid_val = null; }
 
     /**
      * Request update of this compute node. Pushes updates to children,
@@ -154,14 +154,11 @@ class ValueCheckComputeNode extends ComputeNode {
             calc_inputs.set(this.input_translation.get(input.name), input.value);
         }
         let val = this.compute_func(calc_inputs);
-        if (val !== this.value) {
-            super.mark_dirty(2);
-        }
-        else {
-            console.log("soft update");
+        if (val !== null) {
+            if (val !== this.valid_val) { super.mark_dirty(2); } // don't mark dirty if NULL (no update)
+            this.valid_val = val;
         }
         this.value = val;
-
         this.dirty = 0;
         for (const child of this.children) {
             child.mark_input_clean(this.name, this.value);