diff --git a/core/src/main/java/hudson/maven/MavenModule.java b/core/src/main/java/hudson/maven/MavenModule.java
index 822c0ec04d20ccabcb2841bffb8f84cfa46300f4..aa8543d970a1f19abc463e3f6f01e906da79891b 100644
--- a/core/src/main/java/hudson/maven/MavenModule.java
+++ b/core/src/main/java/hudson/maven/MavenModule.java
@@ -299,12 +299,18 @@ public final class MavenModule extends AbstractMavenProject<MavenModule,MavenBui
             modules.put(m.getModuleName(),m);
         }
 
+        // if the build style is the aggregator build, define dependencies against project,
+        // not module.
         AbstractProject dest = getParent().isAggregatorStyleBuild() ? getParent() : this;
 
         for (ModuleName d : dependencies) {
             MavenModule src = modules.get(d);
-            if(src!=null)
-                graph.addDependency(src,dest);
+            if(src!=null) {
+                if(src.getParent().isAggregatorStyleBuild())
+                    graph.addDependency(src.getParent(),dest);
+                else
+                    graph.addDependency(src,dest);
+            }
         }
     }
 
diff --git a/core/src/main/java/hudson/model/DependencyGraph.java b/core/src/main/java/hudson/model/DependencyGraph.java
index bb41b7f4ac03f9bbe5fd6c3b1cb12261e16f38d4..a4a31faa36e6a36ae8c0dd0cb17d08ce165a4833 100644
--- a/core/src/main/java/hudson/model/DependencyGraph.java
+++ b/core/src/main/java/hudson/model/DependencyGraph.java
@@ -187,7 +187,8 @@ public final class DependencyGraph {
             set = new ArrayList<AbstractProject>();
             map.put(src,set);
         }
-        set.add(dst);
+        if(!set.contains(dst))
+            set.add(dst);
     }
 
     private Map<AbstractProject, List<AbstractProject>> finalize(Map<AbstractProject, List<AbstractProject>> m) {