diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CharArrayObjectMapTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CharArrayObjectMapTest.java
new file mode 100644
index 00000000000..093dd4a8d5e
--- /dev/null
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CharArrayObjectMapTest.java
@@ -0,0 +1,74 @@
+/*******************************************************************************
+ * Copyright (c) 2016 Google, Inc and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * 	   Sergey Prigogin (Google) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.core.parser.tests;
+
+import java.util.Random;
+
+import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
+
+import junit.framework.TestCase;
+
+/**
+ * Tests for {@link CharArrayObjectMap}.
+ */
+public class CharArrayObjectMapTest extends TestCase {
+
+	public void testMapAdd() {
+		CharArrayObjectMap map = new CharArrayObjectMap(4);
+		char[] key1 = "key1".toCharArray();
+		Integer value1 = 43;
+		map.put(key1, value1);
+
+		char[] key2 = "key1".toCharArray();
+		Object value2 = map.get(key2);
+		assertEquals(value1, value2);
+
+		for (int i = 0; i < 25; ++i) {
+			map.put(("ikey" + i).toCharArray(), Integer.valueOf(i));
+		}
+
+		for (int i = 0; i < 25; ++i) {
+			Object ivalue1 = map.get(("ikey" + i).toCharArray());
+			assertEquals(i, ivalue1);
+		}
+	}
+
+	public void testDuplicates() {
+		CharArrayObjectMap map = new CharArrayObjectMap(4);
+		String[] keys = new String[] {
+				"a", "b", "c", "c", "value", "value", "context", "context", "result", "d", "e", "f", "g", "h", "i", "j",
+				"k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "z"
+		};
+		for (int i = 0; i < keys.length; i++) {
+			String key = keys[i];
+			map.put(key.toCharArray(), key + i);
+		}
+		assertEquals(29, map.size());
+		for (int i = 0; i < keys.length; i++) {
+			String key = keys[i];
+			if (i != 2 && i != 4 && i != 6 && i != 31) {
+				assertEquals(key + i, map.get(key.toCharArray()));
+			}
+		}
+	}
+
+	public void testCollisionRatio() {
+		Random random = new Random(239);
+		CharArrayObjectMap map = new CharArrayObjectMap(1);
+		for (int i = 0; i < 20000; i++) {
+			int r = random.nextInt();
+			map.put(("key" + Integer.toUnsignedString(i)).toCharArray(), i);
+			double collisionRatio = (double) map.countCollisions() / map.size();
+			assertTrue(String.format("Collision ratio %.3f is unexpectedly high for map size of %d.", collisionRatio, map.size()),
+					collisionRatio <= 0.4);
+		}
+	}
+}
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ObjectMapTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ObjectMapTest.java
index 82cd9192eeb..a269e10b604 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ObjectMapTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ObjectMapTest.java
@@ -14,15 +14,12 @@
  */
 package org.eclipse.cdt.core.parser.tests;
 
-import java.util.Random;
-
-import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
 import org.eclipse.cdt.core.parser.util.ObjectMap;
 
 import junit.framework.TestCase;
 
 /**
- * @author aniefer
+ * Tests for {@link ObjectMap}.
  */
 public class ObjectMapTest extends TestCase {
 
@@ -138,36 +135,4 @@ public class ObjectMapTest extends TestCase {
         insertContents(map, res);
         assertContents(map, res);
     }
-
-	public void testMapAdd() {
-		CharArrayObjectMap map = new CharArrayObjectMap(4);
-		char[] key1 = "key1".toCharArray();
-		Integer value1 = 43;
-		map.put(key1, value1);
-
-		char[] key2 = "key1".toCharArray();
-		Object value2 = map.get(key2);
-		assertEquals(value1, value2);
-
-		for (int i = 0; i < 25; ++i) {
-			map.put(("ikey" + i).toCharArray(), Integer.valueOf(i));
-		}
-
-		for (int i = 0; i < 25; ++i) {
-			Object ivalue1 = map.get(("ikey" + i).toCharArray());
-			assertEquals(i, ivalue1);
-		}
-	}
-
-	public void testCollisionRatio() {
-		Random random = new Random(239);
-		CharArrayObjectMap map = new CharArrayObjectMap(1);
-		for (int i = 0; i < 20000; i++) {
-			int r = random.nextInt();
-			map.put(("key" + Integer.toUnsignedString(i)).toCharArray(), i);
-			double collisionRatio = (double) map.countCollisions() / map.size();
-			assertTrue(String.format("Collision ratio %.3f is unexpectedly high for map size of %d.", collisionRatio, map.size()),
-					collisionRatio <= 0.4);
-		}
-	}
 }
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ParserTestSuite.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ParserTestSuite.java
index 8929bcbb4d5..ce44122bac0 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ParserTestSuite.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ParserTestSuite.java
@@ -11,10 +11,6 @@
  *******************************************************************************/
 package org.eclipse.cdt.core.parser.tests;
 
-import junit.framework.Test;
-import junit.framework.TestCase;
-import junit.framework.TestSuite;
-
 import org.eclipse.cdt.core.model.tests.CModelElementsTests;
 import org.eclipse.cdt.core.model.tests.StructuralCModelElementsTests;
 import org.eclipse.cdt.core.parser.tests.ast2.DOMGCCParserExtensionTestSuite;
@@ -22,6 +18,10 @@ import org.eclipse.cdt.core.parser.tests.ast2.DOMParserTestSuite;
 import org.eclipse.cdt.core.parser.tests.ast2.SemanticsTests;
 import org.eclipse.cdt.core.parser.tests.scanner.ScannerTestSuite;
 
+import junit.framework.Test;
+import junit.framework.TestCase;
+import junit.framework.TestSuite;
+
 /**
  * Combines all tests for the parsers.
  */
@@ -34,6 +34,7 @@ public class ParserTestSuite extends TestCase {
 		suite.addTestSuite(ContentAssistMatcherFactoryTest.class);
 		suite.addTestSuite(CModelElementsTests.class);
 		suite.addTestSuite(StructuralCModelElementsTests.class);
+		suite.addTestSuite(CharArrayObjectMapTest.class);
 		suite.addTestSuite(ObjectMapTest.class);
 		suite.addTestSuite(SemanticsTests.class);
 		suite.addTest(ScannerTestSuite.suite());
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java
index 2152096b560..da8a868d072 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java
@@ -25,7 +25,7 @@ import java.util.function.Consumer;
 /**
  * @author Doug Schaefer
  */
-public class CharArrayObjectMap <T> extends CharTable {
+public class CharArrayObjectMap<T> extends CharTable {
     public static final CharArrayObjectMap<?> EMPTY_MAP = new CharArrayObjectMap<Object>(0) {
         @Override
 		public Object clone() { return this; }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharTable.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharTable.java
index 6280a0b18ae..f33b0fa3d20 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharTable.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharTable.java
@@ -169,7 +169,7 @@ public class CharTable extends HashTable {
 		if (CharArrayUtils.equals(buffer, start, len, keyTable[i]))
 			return i;
 
-		// Follow the next chain
+		// Follow the next chain.
 		for (i = nextTable[i] - 1; i >= 0 && i != nextTable[i] - 1; i = nextTable[i] - 1) {
 			if (CharArrayUtils.equals(buffer, start, len, keyTable[i]))
 				return i;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/HashTable.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/HashTable.java
index 6a773a169dd..abceb621d86 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/HashTable.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/HashTable.java
@@ -173,17 +173,18 @@ public class HashTable implements Cloneable {
 		return offset;
 	}
 
-	protected void linkIntoHashTable(int i, int hash) {
+	protected final void linkIntoHashTable(int i, int hash) {
 		if (nextTable == null)
 			return;
 
-		if (hashTable[hash] == 0) {
+		int j = hashTable[hash];
+		if (j == 0) {
 			hashTable[hash] = i + 1;
 		} else {
 			// Need to link.
-			int j = hashTable[hash] - 1;
+			j--;
 			int k;
-			while ((k = nextTable[j]) != 0) {
+			while ((k = nextTable[j]) != 0 && k != j + 1) {
 				j = k - 1;
 			}
 			nextTable[j] = i + 1;