diff --git a/Source/PluginEditor.h b/Source/PluginEditor.h
index 4620adc..e3b19c5 100644
--- a/Source/PluginEditor.h
+++ b/Source/PluginEditor.h
@@ -218,6 +218,10 @@ private:
     // so the dropdown can be displayed in an order that differs from the
     // parameter's index order (e.g. LP 48dB listed under LP 24dB). This keeps
     // stored parameter indices meaningful while only reordering the menu.
+    //
+    // Note the value-basis split: the constructor reads the NORMALISED value
+    // via getValue(), while parameterChanged() receives the DENORMALISED
+    // value (the choice index itself). Both end at itemId = index + 1.
     class IndexedComboBoxAttachment : public juce::AudioProcessorValueTreeState::Listener,
                                       private juce::ComboBox::Listener {
     public:
@@ -238,9 +242,13 @@ private:
         }
 
         void parameterChanged (const juce::String& parameterID, float newValue) override {
-            if (parameterID == paramId)
-                combo.setSelectedId (1 + juce::roundToInt (newValue * (combo.getNumItems() - 1)),
-                                     juce::dontSendNotification);
+            if (parameterID != paramId)
+                return;
+            // The APVTS delivers the parameter's DENORMALISED value here, which
+            // for an AudioParameterChoice is the choice index (not a normalised
+            // 0..1 value), so map it straight to the itemId (index + 1).
+            combo.setSelectedId (1 + juce::roundToInt (newValue),
+                                 juce::dontSendNotification);
         }
 
         void comboBoxChanged (juce::ComboBox* cb) override {