Index: lib/rtl/unicode.c
===================================================================
--- lib/rtl/unicode.c	(revision 41120)
+++ lib/rtl/unicode.c	(working copy)
@@ -395,7 +395,38 @@
     }
 }
 
+
 /*
+ * @implemented
+ * 
+ * NOTES
+ *  Checks the oem-string to match the uincoded-string.
+ *  Function who convert unicode string to oem string will set a questionmark
+ *  when the character are unkown. So check it against the unicode string
+ *  and return false when the uncode string not contain an questionmark.
+ */
+BOOLEAN
+NTAPI
+RtlpDidUnicodeToOemWork(PUNICODE_STRING  UnicodeString,POEM_STRING OemString)
+{
+   ULONG i;
+   if ((OemString != NULL) && (OemString->Buffer != NULL))
+   {
+      i = 0;
+      while (OemString->Buffer[i]!=0)
+      {
+         if ((OemString->Buffer[i]=='?') && (UnicodeString->Buffer[i]!=L'?'))
+         {
+            return FALSE;
+         }
+         i++;
+      }
+      return TRUE;
+   }
+   return FALSE;
+}
+
+/*
 * @unimplemented
 */
 BOOLEAN
@@ -1534,8 +1565,14 @@
                               UniSource->Buffer,
                               UniSource->Length);
 
-    /* FIXME: Check if everything mapped correctly and
-     * return STATUS_UNMAPPABLE_CHARACTER */
+    if (NT_SUCCESS(Status))
+    {
+       /* check for unmapped character */
+       if (RtlpDidUnicodeToOemWork(UniSource,OemDest) == FALSE)
+       {
+          Status = STATUS_UNMAPPABLE_CHARACTER;
+       }
+    }
 
     if (!NT_SUCCESS(Status) && AllocateDestinationString)
     {