diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/BTreeTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/BTreeTests.java
index a05e76e02e5..e04ac4b3e46 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/BTreeTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/BTreeTests.java
@@ -53,6 +53,7 @@ public class BTreeTests extends BaseTestCase {
 	protected void init(int degree) throws Exception {
 		dbFile = File.createTempFile("pdomtest", "db");
 		db = new Database(dbFile, new ChunkCache(), 0);
+		db.setWritable();
 		rootRecord = Database.DATA_AREA;
 		comparator = new BTMockRecordComparator();
 		btree = new BTree(db, rootRecord, degree, comparator);
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBPropertiesTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBPropertiesTests.java
index 213eb2fa4cf..c5318015536 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBPropertiesTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBPropertiesTests.java
@@ -38,6 +38,7 @@ public class DBPropertiesTests extends BaseTestCase {
 		dbLoc = File.createTempFile("test", "db");
 		dbLoc.deleteOnExit();
 		db = new Database(dbLoc, new ChunkCache(), 0);
+		db.setWritable();
 	}
 	
 	protected void tearDown() throws Exception {
@@ -45,6 +46,7 @@ public class DBPropertiesTests extends BaseTestCase {
 	}
 	
 	public void testBasic() throws CoreException {
+		db.setWritable();
 		DBProperties properties = new DBProperties(db);
 		Properties expected = System.getProperties();
 		for(Iterator i = expected.keySet().iterator(); i.hasNext(); ) {
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBTest.java
index e35e8cb1ad4..a2b3b75ea67 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DBTest.java
@@ -127,6 +127,7 @@ public class DBTest extends BaseTestCase {
 		File f = getTestDir().append("testStrings.dat").toFile();
 		f.delete();
 		final Database db = new Database(f, new ChunkCache(), 0);
+		db.setWritable();
 
 		String[] names = {
 				"ARLENE",
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
index 5bfb7a1fe8b..c94dc922957 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
@@ -249,6 +249,7 @@ public class PDOM extends PlatformObject implements IIndexFragment, IPDOM {
 	}
 	
 	void reloadFromFile(File file) throws CoreException {
+		assert lockCount < 0;	// must have write lock.
 		File oldFile= fPath;
 		fLinkageIDCache.clear();
 		try {
@@ -257,6 +258,7 @@ public class PDOM extends PlatformObject implements IIndexFragment, IPDOM {
 			CCorePlugin.log(e);
 		}
 		loadDatabase(file, db.getChunkCache());
+		db.setWritable();
 		oldFile.delete();
 	}		
 
@@ -750,7 +752,7 @@ public class PDOM extends PlatformObject implements IIndexFragment, IPDOM {
 		db.resetCacheCounters();
 	}
 
-	public void flush() throws CoreException {
+	protected void flush() throws CoreException {
 		db.flush();
 	}
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
index bdabb5ec383..0f95cc08e81 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
@@ -72,6 +72,10 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 		super.clear();
 	}
 	
+	public void flush() throws CoreException {
+		super.flush();
+	}
+	
 	public PDOMBinding addBinding(IASTName name) throws CoreException {
 		PDOMBinding result= null;
 		PDOMLinkage linkage= createLinkage(name.getLinkage().getID());
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/db/Chunk.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/db/Chunk.java
index fd90a1488d1..ef28bed112c 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/db/Chunk.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/db/Chunk.java
@@ -57,6 +57,7 @@ final class Chunk {
 	}
 
 	public void putByte(int offset, byte value) {
+		assert fLocked;
 		fDirty= true;
 		fBuffer.put(offset % Database.CHUNK_SIZE, value);
 	}
@@ -73,12 +74,14 @@ final class Chunk {
 	}
 	
 	public void putBytes(int offset, byte[] bytes) {
+		assert fLocked;
 		fDirty= true;
 		fBuffer.position(offset % Database.CHUNK_SIZE);
 		fBuffer.put(bytes, 0, bytes.length);
 	}
 	
 	public void putInt(int offset, int value) {
+		assert fLocked;
 		fDirty= true;
 		fBuffer.putInt(offset % Database.CHUNK_SIZE, value);
 	}
@@ -88,6 +91,7 @@ final class Chunk {
 	}
 
 	public void putShort(int offset, short value) {
+		assert fLocked;
 		fDirty= true;
 		fBuffer.putShort(offset % Database.CHUNK_SIZE, value);
 	}
@@ -101,11 +105,13 @@ final class Chunk {
 	}
 
 	public void putLong(int offset, long value) {
+		assert fLocked;
 		fDirty= true;
 		fBuffer.putLong(offset % Database.CHUNK_SIZE, value);
 	}
 	
 	public void putChar(int offset, char value) {
+		assert fLocked;
 		fDirty= true;
 		fBuffer.putChar(offset % Database.CHUNK_SIZE, value);
 	}
@@ -120,6 +126,7 @@ final class Chunk {
 	}
 	
 	void clear(int offset, int length) {
+		assert fLocked;
 		fDirty= true;
 		fBuffer.position(offset % Database.CHUNK_SIZE);
 		fBuffer.put(new byte[length]);