diff --git a/platform/lang-impl/src/com/intellij/psi/impl/source/tree/LazyParseableElement.java b/platform/lang-impl/src/com/intellij/psi/impl/source/tree/LazyParseableElement.java
index 134b12cb0612..e78fc6dc9af3 100644
--- a/platform/lang-impl/src/com/intellij/psi/impl/source/tree/LazyParseableElement.java
+++ b/platform/lang-impl/src/com/intellij/psi/impl/source/tree/LazyParseableElement.java
@@ -20,6 +20,7 @@
 package com.intellij.psi.impl.source.tree;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.tree.ILazyParseableElementType;
@@ -167,6 +168,8 @@ public class LazyParseableElement extends CompositeElement {
       LOG.error("Chameleons must not be parsed till they're in file tree");
     }
 
+    ApplicationManager.getApplication().assertReadAccessAllowed();
+
     ILazyParseableElementType type = (ILazyParseableElementType)getElementType();
     ASTNode parsedNode = type.parseContents(this);
     myText = null;