diff --git a/src/main/org/apache/tools/ant/taskdefs/Javadoc.java b/src/main/org/apache/tools/ant/taskdefs/Javadoc.java
index 856e809b0..f0a6fa9c3 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Javadoc.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Javadoc.java
@@ -2013,7 +2013,9 @@ public class Javadoc extends Task {
                 String sourceFileName = sf.getFile().getAbsolutePath();
                 if (useExternalFile) {
                     if (javadoc4 && sourceFileName.indexOf(" ") > -1) {
-                        srcListWriter.println("\"" + sourceFileName + "\"");
+                        String name = 
+                            sourceFileName.replace(File.separatorChar, '/');
+                        srcListWriter.println("\"" + name + "\"");
                     } else {
                         srcListWriter.println(sourceFileName);
                     }