diff --git a/main/HPSF/MutableSection.cs b/main/HPSF/MutableSection.cs
index 6f7407fa7..aed706511 100644
--- a/main/HPSF/MutableSection.cs
+++ b/main/HPSF/MutableSection.cs
@@ -230,7 +230,10 @@ public void SetProperty(Property p)
         {
             long id = p.ID;
             RemoveProperty(id);
-            preprops.Add(p);
+            if (p.Value != null)
+            {
+                preprops.Add(p);
+            }
             dirty = true;
         }