diff --git a/nondex-test/src/test/java/edu/illinois/nondex/core/AbstractCollectionTest.java b/nondex-test/src/test/java/edu/illinois/nondex/core/AbstractCollectionTest.java
index 028f849d..faec7293 100644
--- a/nondex-test/src/test/java/edu/illinois/nondex/core/AbstractCollectionTest.java
+++ b/nondex-test/src/test/java/edu/illinois/nondex/core/AbstractCollectionTest.java
@@ -29,6 +29,8 @@ a copy of this software and associated documentation files (the
 
 package edu.illinois.nondex.core;
 
+import java.util.Arrays;
+
 import edu.illinois.nondex.shuffling.ControlNondeterminism;
 
 import org.junit.Assert;
@@ -56,16 +58,22 @@ protected void assertParameterized(T ds, Object derived, String str) {
         }
     }
 
-    protected void assertEqualstUnordered(String msg, String expected, String actual) {
-        Assert.assertEquals(msg + ": " + expected + " =/= " + actual, expected.length(), actual.length());
-        String trimmed = expected.substring(1, expected.length() - 1);
+    private String[] formatString(String msg) {
+        String trimmed = msg.substring(1, msg.length() - 1);
         String[] elems = trimmed.split(",");
-        // TODO(gyori): fix and make this more robust. It does not check duplicates, substrings, etc.
         for (int i = 0; i < elems.length; i++) {
             elems[i] = elems[i].trim();
-            Assert.assertTrue(msg + ": " + trimmed + " =/= " + actual, actual.contains(elems[i]));
         }
+        return elems;
+    }
 
+    protected void assertEqualstUnordered(String msg, String expected, String actual) {
+        String trimmed = expected.substring(1, expected.length() - 1);
+        String[] actualTokenized = this.formatString(actual);
+        String[] expectedTokenized = this.formatString(expected);
 
+        Arrays.sort(actualTokenized);
+        Arrays.sort(expectedTokenized);
+        Assert.assertArrayEquals(msg + ": " + trimmed + " =/= " + actual, expectedTokenized, actualTokenized);
     }
 }
diff --git a/nondex-test/src/test/java/edu/illinois/nondex/core/HashMapTest.java b/nondex-test/src/test/java/edu/illinois/nondex/core/HashMapTest.java
index 9fc689d0..7ec0294b 100644
--- a/nondex-test/src/test/java/edu/illinois/nondex/core/HashMapTest.java
+++ b/nondex-test/src/test/java/edu/illinois/nondex/core/HashMapTest.java
@@ -148,6 +148,12 @@ public void testEntrySet() {
                 "{0=0, 1=1, 2=2, 3=3, 4=4, 5=5, 6=6, 7=7, 8=8, 9=9}", entrySet.toString());
     }
 
+    @Test(expected = AssertionError.class)
+    public void testAssertEqualsUnorderedFailsWithDuplicates() {
+        this.assertEqualstUnordered("the strings are not a permutation of each other",
+            "{0=0, 0=0, 1=1, 2=2, 3=3}", "{0=0, 1=1, 2=2, 3=3}");
+    }
+
     @Test
     public void testEntrySetParametrized() {
         Map<Integer, Integer> map = this.createResizedDS();