diff --git a/README.md b/README.md
index 9b6df64a..7c89c36a 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ this fork is not recommended.
 
 You can try `ant all` or `ant jar-jme`, but there is no guarantee that it
 will even compile (though that may be fixed in a future version).
+The `TODO` file can contain information about some known issues.
 
 This fork aims to fix some issues met with luaj 3.0.2, still present in 
 [luaj/luaj](https://github.com/luaj/luaj) at
diff --git a/TODO b/TODO
new file mode 100644
index 00000000..d8ed0e6f
--- /dev/null
+++ b/TODO
@@ -0,0 +1,20 @@
+The current version doesn't compile with:
+ant jar-jme|all
+
+The Java compiler complains with an obscure error:
+    [javac] /Users/ducos/Projects/luaj/build/jme/src/org/luaj/vm2/LuaValue.java:532: error: cannot access StringBuilder
+    [javac] 	public String  tojstring()           { return typename() + ": " + Integer.toHexString(hashCode()); }
+
+This is because, in recent versions of Java, the concatenation of strings is automatically performed
+with java.lang.StringBuilder
+
+Unfortunately, this class is not available in the JME environment.
+
+A workaround would be to replaced the + concatenation with the String.concat() method, like this:
+
+-       public String  tojstring()           { return typename() + ": " + Integer.toHexString(hashCode()); }
++       public String  tojstring()           { return typename().concat(": ").concat(Integer.toHexString(hashCode())); }
+
+But it has to be done everywhere in the code.
+
+Maybe there is a more straightforward method, with a compiler's flag.