--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties	Mon May 16 15:41:20 2016 +0200
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties	Mon May 16 15:41:57 2016 +0200
@@ -522,8 +522,9 @@
 compiler.err.illegal.char=\
     illegal character: ''{0}''
 
+# 0: string, 1: string
 compiler.err.illegal.char.for.encoding=\
-    unmappable character for encoding {0}
+    unmappable character (0x{0}) for encoding {1}
 
 # 0: set of modifier, 1: set of modifier
 compiler.err.illegal.combination.of.modifiers=\