diff --git a/src/org/ntlab/deltaViewer/DeltaAliasCollector.java b/src/org/ntlab/deltaViewer/DeltaAliasCollector.java
index 502836e..b5a4369 100644
--- a/src/org/ntlab/deltaViewer/DeltaAliasCollector.java
+++ b/src/org/ntlab/deltaViewer/DeltaAliasCollector.java
@@ -303,23 +303,23 @@
 	private Map<MethodExecution, Set<MethodExecution>> collectNewToOldMethodExecutionMap(List<Alias> oldAliasList, List<Alias> newAliasList) {
 		Map<MethodExecution, Set<MethodExecution>> newToOldMethodExecMap = new HashMap<>();
 		int oldIdx = 0, newIdx = 0;
-		Alias lastMatchedAlias = null;
+		Alias lastMatchedNextAlias = newAliasList.get(newIdx);
 		for (oldIdx = 0; oldIdx < oldAliasList.size(); oldIdx++) {
 			Alias oldAlias = oldAliasList.get(oldIdx);
 			Alias newAlias = newAliasList.get(newIdx);
 			if (oldAlias.equals(newAlias)) {
-				lastMatchedAlias = newAlias;
-				newIdx++;
+				if (newIdx + 1 < newAliasList.size()) newIdx++;
+				lastMatchedNextAlias = newAliasList.get(newIdx);
 			} else {
 				MethodExecution oldMethodExec = oldAlias.getMethodExecution();
-				MethodExecution newMethodExec = lastMatchedAlias.getMethodExecution();
+				MethodExecution newMethodExec = lastMatchedNextAlias.getMethodExecution();
 				if (!newToOldMethodExecMap.containsKey(newMethodExec)) {
 					newToOldMethodExecMap.put(newMethodExec, new HashSet<>());
 					newToOldMethodExecMap.get(newMethodExec).add(oldMethodExec);
 				} else {
 					newToOldMethodExecMap.get(newMethodExec).add(oldMethodExec);
 				}
-				if (!oldAliasList.contains(newAlias)) newIdx++;
+				if (!oldAliasList.contains(newAlias) && newIdx + 1 < newAliasList.size()) newIdx++;
 			}
 		}
 		return newToOldMethodExecMap;