diff --git a/platform/lang-impl/src/com/intellij/ide/projectView/impl/AbstractProjectViewPane.java b/platform/lang-impl/src/com/intellij/ide/projectView/impl/AbstractProjectViewPane.java
index 044844aa7276..5acd883f6ba9 100644
--- a/platform/lang-impl/src/com/intellij/ide/projectView/impl/AbstractProjectViewPane.java
+++ b/platform/lang-impl/src/com/intellij/ide/projectView/impl/AbstractProjectViewPane.java
@@ -497,6 +497,9 @@ public abstract class AbstractProjectViewPane implements DataProvider, Disposabl
       if (!treeState.isEmpty()) {
         myReadTreeState.put(getSubId(), treeState);
       }
+      else {
+        myReadTreeState.remove(getSubId());
+      }
     }
   }