diff --git a/src/org/ntlab/traceDebugger/Variable.java b/src/org/ntlab/traceDebugger/Variable.java
index 0156d8d..125ff5f 100644
--- a/src/org/ntlab/traceDebugger/Variable.java
+++ b/src/org/ntlab/traceDebugger/Variable.java
@@ -132,6 +132,10 @@
 	public TracePoint getBeforeTracePoint() {
 		return before;
 	}
+
+	public void setBeforeTracePoint(TracePoint before) {
+		this.before = before;
+	}
 	
 	public Variable getParent() {
 		return parent;
diff --git a/src/org/ntlab/traceDebugger/Variables.java b/src/org/ntlab/traceDebugger/Variables.java
index 915b369..b0e5bbb 100644
--- a/src/org/ntlab/traceDebugger/Variables.java
+++ b/src/org/ntlab/traceDebugger/Variables.java
@@ -155,19 +155,20 @@
 	}
 		
 	public void updateForDifferential(TracePoint from, TracePoint to, boolean isReturned) {
-		updateForDifferential();
+		updateForDifferential(to);
 		resetSpecialValues();
 		createSpecialVariables(from, to, isReturned);
 	}
 	
-	private void updateForDifferential() {
+	private void updateForDifferential(TracePoint before) {
 		for (Variable variable : roots) {
-			updateForDifferential(variable, new HashSet<String>());
+			updateForDifferential(variable, new HashSet<String>(), before);
 		}
 		containerIdToDifferentialUpdateTracePoints.clear();
 	}
 
-	private void updateForDifferential(Variable variable, Set<String> hasCheckedObjectIdSet) {
+	private void updateForDifferential(Variable variable, Set<String> hasCheckedObjectIdSet, TracePoint before) {
+		variable.setBeforeTracePoint(before);
 		Set<String> containerIdList = containerIdToDifferentialUpdateTracePoints.keySet();
 		String containerId = variable.getContainerId();
 		if (containerIdList.contains(containerId)) {
@@ -191,7 +192,7 @@
 		hasCheckedObjectIdSetOnNext.add(variable.getContainerId());
 		for (Variable child : variable.getChildren()) {
 			if (hasCheckedObjectIdSetOnNext.contains(child.getContainerId())) continue;
-			updateForDifferential(child, hasCheckedObjectIdSetOnNext);
+			updateForDifferential(child, hasCheckedObjectIdSetOnNext, before);
 		}
 	}