diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java
index 52c0ed51bdc..eeec770469f 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java
@@ -562,6 +562,8 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 			info= createFileInfo(key, null);
 		}
 		info.fIndexFile= ifile;
+		info.fDirectives= null;
+		info.fPreprocessingDirectives= null;
 		info.fRequestUpdate= true;
 		info.fIsUpdated= false;
 	}