diff --git a/ModelMultiParticlePersistFX.cs b/ModelMultiParticlePersistFX.cs
index b50f8d4..2fb9e7d 100644
--- a/ModelMultiParticlePersistFX.cs
+++ b/ModelMultiParticlePersistFX.cs
@@ -73,6 +73,7 @@ public class ModelMultiParticlePersistFX : EffectBehaviour
     [Persistent]
     public bool fixedEmissions = true;
 
+    // The time between Update()s (in seconds).
     private float variableDeltaTime;
     
     public FXCurve emission = new FXCurve("emission", 1f);