Index: src/main/java/org/apache/maven/plugin/resources/remote/ProcessRemoteResourcesMojo.java
===================================================================
--- src/main/java/org/apache/maven/plugin/resources/remote/ProcessRemoteResourcesMojo.java	(revision 1293977)
+++ src/main/java/org/apache/maven/plugin/resources/remote/ProcessRemoteResourcesMojo.java	(working copy)
@@ -740,11 +740,21 @@
                 try
                 {
                     Set<Artifact> depArtifacts = p.createArtifacts( artifactFactory, null, null );
-                    p.setDependencyArtifacts( depArtifacts );
-                    
+
                     if ( depArtifacts != null && !depArtifacts.isEmpty() )
                     {
-                        artifacts.addAll( depArtifacts );
+                        for ( Artifact artifact : depArtifacts )
+                        {
+                            if ( artifact.getVersion() == null && artifact.getVersionRange() != null )
+                            {
+                                // Version is required for equality comparison between artifacts,
+                                // but it is not needed for our purposes of filtering out
+                                // transitive dependencies (which requires only groupId/artifactId).
+                                // Therefore set an arbitrary version if missing.
+                                artifact.setResolvedVersion( Artifact.LATEST_VERSION );
+                            }
+                            artifacts.add( artifact );
+                        }
                     }
                 }
                 catch ( InvalidDependencyVersionException e )