diff --git a/src/checkstyle/com/puppycrawl/tools/checkstyle/checks/metrics/AbstractClassCouplingCheck.java b/src/checkstyle/com/puppycrawl/tools/checkstyle/checks/metrics/AbstractClassCouplingCheck.java
index 74ed47d5a..d07ac0aca 100644
--- a/src/checkstyle/com/puppycrawl/tools/checkstyle/checks/metrics/AbstractClassCouplingCheck.java
+++ b/src/checkstyle/com/puppycrawl/tools/checkstyle/checks/metrics/AbstractClassCouplingCheck.java
@@ -1,6 +1,6 @@
 ////////////////////////////////////////////////////////////////////////////////
 // checkstyle: Checks Java source code for adherence to a set of rules.
-// Copyright (C) 2001-2005  Oliver Burn
+// Copyright (C) 2001-2007  Oliver Burn
 //
 // This library is free software; you can redistribute it and/or
 // modify it under the terms of the GNU Lesser General Public
@@ -28,6 +28,7 @@ import com.puppycrawl.tools.checkstyle.checks.CheckUtils;
 import java.util.HashSet;
 import java.util.Set;
 import java.util.Stack;
+import java.util.TreeSet;
 
 /**
  * Base class for coupling calculation.
@@ -202,8 +203,11 @@ public abstract class AbstractClassCouplingCheck extends Check
      */
     private class Context
     {
-        /** Set of referenced classes. */
-        private final Set mReferencedClassNames = new HashSet();
+        /**
+         * Set of referenced classes.
+         * Sorted by name for predictable error messages in unit tests.
+         */
+        private final Set mReferencedClassNames = new TreeSet();
         /** Own class name. */
         private final String mClassName;
         /* Location of own class. (Used to log violations) */
diff --git a/src/tests/com/puppycrawl/tools/checkstyle/checks/metrics/ClassDataAbstractionCouplingCheckTest.java b/src/tests/com/puppycrawl/tools/checkstyle/checks/metrics/ClassDataAbstractionCouplingCheckTest.java
index ea4feb846..78bbd63f5 100644
--- a/src/tests/com/puppycrawl/tools/checkstyle/checks/metrics/ClassDataAbstractionCouplingCheckTest.java
+++ b/src/tests/com/puppycrawl/tools/checkstyle/checks/metrics/ClassDataAbstractionCouplingCheckTest.java
@@ -14,7 +14,7 @@ public class ClassDataAbstractionCouplingCheckTest extends BaseCheckTestCase
         checkConfig.addAttribute("max", "0");
 
         String[] expected = {
-            "6:1: Class Data Abstraction Coupling is 4 (max allowed is 0) classes [AnotherInnerClass, HashMap, InnerClass, HashSet].",
+            "6:1: Class Data Abstraction Coupling is 4 (max allowed is 0) classes [AnotherInnerClass, HashMap, HashSet, InnerClass].",
             "7:5: Class Data Abstraction Coupling is 1 (max allowed is 0) classes [ArrayList].",
             "27:1: Class Data Abstraction Coupling is 2 (max allowed is 0) classes [HashMap, HashSet].",
         };