The implementation of Comparable.compareTo(Object) is faulty regarding the handling of version numbers where a build number is present but zero. Here's a unit test to demonstrate: DefaultArtifactVersion v1 = new DefaultArtifactVersion("2.0"); DefaultArtifactVersion v2 = new DefaultArtifactVersion("2.0-0"); DefaultArtifactVersion v3 = new DefaultArtifactVersion("2.0-alpha1"); // v1 and v2 are equal assertTrue( v1.compareTo(v2) == 0 ); assertTrue( v2.compareTo(v1) == 0 ); // v1 is newer than v3 assertTrue( v1.compareTo(v3) > 0 ); assertTrue( v3.compareTo(v1) < 0 ); // ergo, v2 should also be newer than v3 assertTrue( v2.compareTo(v3) > 0 ); // FAILS!! returns 0 (equal) assertTrue( v3.compareTo(v1) < 0 ); // succeeds This test demonstrates this behavior violates symmetry and transitivity. Luckily, the fix is easy. A small change to the compareTo method to consider qualifiers before build numbers relieves this issue. I have a patch that I'll submit as soon as I have the issue number.