diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
index d7de5822e..1da1f0116 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
@@ -1388,10 +1388,23 @@ public class GanttDiagramGraph<V, D extends IDependency<V>> implements
                     result.addAll(getDependenciesConstraintsFor(getPrimaryPoint()));
                     result.addAll(getTaskConstraints(getPrimaryPoint()));
                 }
-                result.addAll(globalStartConstraints);
+                result.addAll(getGlobalConstraintsToApply(getPrimaryPoint()));
                 return result;
             }
 
+            private Collection<Constraint<GanttDate>> getGlobalConstraintsToApply(
+                    Point point) {
+                Validate.isTrue(isSupportedPoint(point));
+                switch (point) {
+                case START:
+                    return globalStartConstraints;
+                case END:
+                    return globalEndConstraints;
+                default:
+                    throw new RuntimeException("shouldn't happen");
+                }
+            }
+
             protected List<Constraint<GanttDate>> getConstraintsForSecondaryPoint() {
                 return getDependenciesConstraintsFor(getSecondaryPoint());
             }