diff --git a/src/main/org/apache/tools/ant/taskdefs/UpToDate.java b/src/main/org/apache/tools/ant/taskdefs/UpToDate.java
index a898eff80..33ed1098b 100644
--- a/src/main/org/apache/tools/ant/taskdefs/UpToDate.java
+++ b/src/main/org/apache/tools/ant/taskdefs/UpToDate.java
@@ -177,13 +177,15 @@ public class UpToDate extends MatchingTask {
     protected boolean scanDir(File srcDir, String files[]) {
         SourceFileScanner sfs = new SourceFileScanner(this);
         FileNameMapper mapper = null;
+        File dir = srcDir;
         if (mapperElement == null) {
             MergingMapper mm = new MergingMapper();
             mm.setTo(_targetFile.getAbsolutePath());
             mapper = mm;
+            dir = null;
         } else {
             mapper = mapperElement.getImplementation();
         }
-        return sfs.restrict(files, srcDir, null, mapper).length == 0;
+        return sfs.restrict(files, srcDir, dir, mapper).length == 0;
     }
 }