diff --git a/normal/charset.c b/normal/charset.c
index 7c455a357..00bbcb815 100644
--- a/normal/charset.c
+++ b/normal/charset.c
@@ -16,6 +16,25 @@
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/*
+  Current problems with Unicode rendering: 
+  - B and BN bidi type characters (ignored)
+  - Mc type characters with combining class 0 (treated as non-combining)
+  - Mn type characters with combining class 0 (treated as non-combining)
+  - Me type characters with combining class 0 (treated as non-combining)
+  - Cf type characters (ignored)
+  - Cc type characters (ignored)
+  - Line-breaking rules (e.g. Zs type characters)
+  - Indic languages
+  - Arabic shaping
+  - Zl and Zp characters
+  - Combining characters of types 7, 8, 9, 21, 27, 28, 29, 30, 31,
+  32, 33, 34, 35, 36, 84, 91, 103, 107, 118, 122, 129, 130, 132,
+  218, 224, 226, 233, 234
+  - Private use surrogates
+  - Private use characters (not really a problem)
+ */
+
 /* Convert a (possibly null-terminated) UTF-8 string of at most SRCSIZE
    bytes (if SRCSIZE is -1, it is ignored) in length to a UTF-16 string.
    Return the number of characters converted. DEST must be able to hold
diff --git a/util/import_unicode.py b/util/import_unicode.py
index 0fc36c5c2..e0e53b655 100644
--- a/util/import_unicode.py
+++ b/util/import_unicode.py
@@ -45,12 +45,35 @@ for line in infile:
         print ("UnicodeData.txt uses combination type %d. Conflict." \
                    % curcombtype)
         raise
+    if sp[2] != "Lu" and sp[2] != "Ll" and sp[2] != "Lt" and sp[2] != "Lm" \
+            and sp[2] != "Lo"\
+            and sp[2] != "Me" and sp[2] != "Mc" and sp[2] != "Mn" \
+            and sp[2] != "Nd" and sp[2] != "Nl" and sp[2] != "No" \
+            and sp[2] != "Pc" and sp[2] != "Pd" and sp[2] != "Ps" \
+            and sp[2] != "Pe" and sp[2] != "Pi" and sp[2] != "Pf" \
+            and sp[2] != "Po" \
+            and sp[2] != "Sm" and sp[2] != "Sc" and sp[2] != "Sk" \
+            and sp[2] != "So"\
+            and sp[2] != "Zs" and sp[2] != "Zl" and sp[2] != "Zp" \
+            and sp[2] != "Cc" and sp[2] != "Cf" and sp[2] != "Cs" \
+            and sp[2] != "Co":
+        print ("WARNING: Unknown type %s" % sp[2])
     if curcombtype == 0 and sp[2] == "Me":
         curcombtype = 253
     if curcombtype == 0 and sp[2] == "Mc":
         curcombtype = 254
     if curcombtype == 0 and sp[2] == "Mn":
         curcombtype = 255
+    if (curcombtype >= 2 and curcombtype <= 6) \
+            or (curcombtype >= 37 and curcombtype != 84 and curcombtype != 91  and curcombtype != 103 and curcombtype != 107 and curcombtype != 118 and curcombtype != 122 and curcombtype != 129 and curcombtype != 130 and curcombtype != 132 and curcombtype != 202 and \
+                curcombtype != 214 and curcombtype != 216 and \
+                curcombtype != 218 and curcombtype != 220 and \
+                curcombtype != 222 and curcombtype != 224 and curcombtype != 226 and curcombtype != 228 and \
+                curcombtype != 230 and curcombtype != 232 and curcombtype != 233 and \
+                curcombtype != 234 and \
+                curcombtype != 240 and curcombtype != 253 and \
+                curcombtype != 254 and curcombtype != 255):
+        print ("WARNING: Unknown combining type %d" % curcombtype)
     if lastcode + 1 != curcode or curbiditype != lastbiditype \
             or curcombtype != lastcombtype or curmirrortype != lastmirrortype:
         if begincode != -2 and (lastbiditype != "L" or lastcombtype != 0 or \