diff --git a/classpath/java-io.cpp b/classpath/java-io.cpp
index d15fe1489b..49c6937c81 100644
--- a/classpath/java-io.cpp
+++ b/classpath/java-io.cpp
@@ -20,6 +20,8 @@
 
 #ifdef PLATFORM_WINDOWS
 
+#  define UNICODE
+
 #  include <windows.h>
 #  include <io.h>
 #  include <direct.h>