Index: /FCKeditor.Java/trunk/java-core/src/main/java/net/fckeditor/FCKeditor.java
===================================================================
--- /FCKeditor.Java/trunk/java-core/src/main/java/net/fckeditor/FCKeditor.java	(revision 3520)
+++ /FCKeditor.Java/trunk/java-core/src/main/java/net/fckeditor/FCKeditor.java	(revision 3521)
@@ -130,7 +130,7 @@
 		if (Utils.isEmpty(instanceName))
 			throw new IllegalArgumentException("instanceName cannot be empty");
-		if (!instanceName.matches("[A-Za-z][A-Za-z0-9:_.-]*"))
+		if (!instanceName.matches("\\p{Alpha}[\\p{Alnum}:_.-]*"))
 			throw new IllegalArgumentException(
-					"instanceName must be a valid XHTML id containing only [A-Za-z][A-Za-z0-9:_.-]*");
+					"instanceName must be a valid XHTML id containing only \"\\p{Alpha}[\\p{Alnum}:_.-]*\"");
 		this.instanceName = instanceName;
 	}