diff --git a/ChangeLog b/ChangeLog
index 7ca7f24..5933f06 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -48,6 +48,10 @@ Some bugs in the refactored code were subsequently fixed before release:
   (b) In utf mode, the length of a *MARK (or other verb) name was being checked
       in characters instead of code units, which could lead to bad code being 
       compiled, leading to unpredictable behaviour. 
+      
+  (c) In extended /x mode, characters whose code was greater than 255 caused
+      a lookup outside one of the global tables. A similar bug existed for wide 
+      characters in *VERB names.  
 
 4. Back references are now permitted in lookbehind assertions when there are 
 no duplicated group numbers (that is, (?| has not been used), and, if the 
diff --git a/src/pcre2_compile.c b/src/pcre2_compile.c
index a76ca0f..b7df32d 100644
--- a/src/pcre2_compile.c
+++ b/src/pcre2_compile.c
@@ -2226,7 +2226,9 @@ while (ptr < ptrend)
   and \E and escaped characters are allowed (no character types such as \d). If
   PCRE2_EXTENDED is also set, we must ignore white space and # comments. Do
   this by not entering the special (*VERB:NAME) processing - they are then
-  picked up below. */
+  picked up below. Note that c is a character, not a code unit, so we must not
+  use MAX_255 to test its size because MAX_255 tests code units and is assumed
+  TRUE in 8-bit mode. */
 
   if (inverbname &&
        (
@@ -2234,7 +2236,7 @@ while (ptr < ptrend)
         ((options & (PCRE2_EXTENDED | PCRE2_ALT_VERBNAMES)) !=
                     (PCRE2_EXTENDED | PCRE2_ALT_VERBNAMES)) ||
         /* OR: character > 255 */
-        !MAX_255(c) ||
+        c > 255 ||
         /* OR: not a # comment or white space */
         (c != CHAR_NUMBER_SIGN && (cb->ctypes[c] & ctype_space) == 0)
        ))
@@ -2306,11 +2308,13 @@ while (ptr < ptrend)
       }
     }
 
-  /* Skip over whitespace and # comments in extended mode. */
+  /* Skip over whitespace and # comments in extended mode. Note that c is a
+  character, not a code unit, so we must not use MAX_255 to test its size
+  because MAX_255 tests code units and is assumed TRUE in 8-bit mode. */
 
   if ((options & PCRE2_EXTENDED) != 0)
     {
-    if (MAX_255(c) && (cb->ctypes[c] & ctype_space) != 0) continue;
+    if (c < 256 && (cb->ctypes[c] & ctype_space) != 0) continue;
     if (c == CHAR_NUMBER_SIGN)
       {
       while (ptr < ptrend)
@@ -8866,7 +8870,7 @@ if (pattern == NULL)
   *errorptr = ERR16;
   return NULL;
   }
-  
+
 /* Check that all undefined public option bits are zero. */
 
 if ((options & ~PUBLIC_COMPILE_OPTIONS) != 0)
diff --git a/src/pcre2_intmodedep.h b/src/pcre2_intmodedep.h
index d062144..0579bd6 100644
--- a/src/pcre2_intmodedep.h
+++ b/src/pcre2_intmodedep.h
@@ -200,11 +200,11 @@ arithmetic results in a signed value. Hence the cast. */
 #endif
 
 /* Other macros that are different for 8-bit mode. The MAX_255 macro checks
-whether its argument is less than 256. The maximum length of a MARK name must
-fit in one code unit; currently it is set to 255 or 65535. The TABLE_GET macro
-is used to access elements of tables containing exactly 256 items. When code
-points can be greater than 255, a check is needed before accessing these
-tables. */
+whether its argument, which is assumed to be one code unit, is less than 256.
+The maximum length of a MARK name must fit in one code unit; currently it is
+set to 255 or 65535. The TABLE_GET macro is used to access elements of tables
+containing exactly 256 items. When code points can be greater than 255, a check
+is needed before accessing these tables. */
 
 #if PCRE2_CODE_UNIT_WIDTH == 8
 #define MAX_255(c) TRUE
diff --git a/testdata/testinput5 b/testdata/testinput5
index a55fb32..7e6e6a7 100644
--- a/testdata/testinput5
+++ b/testdata/testinput5
@@ -1738,4 +1738,8 @@
 /../utf,auto_callout
     \n\x{123}\x{123}\x{123}\x{123}
 
+# This tests processing wide characters in extended mode.
+
+/XȀ/x,utf
+
 # End of testinput5 
diff --git a/testdata/testoutput5 b/testdata/testoutput5
index 30bfb02..bd85613 100644
--- a/testdata/testoutput5
+++ b/testdata/testoutput5
@@ -4182,4 +4182,8 @@ Failed: error 125 at offset 2: lookbehind assertion is not fixed length
  +2       ^             ^                  
  0: \x{123}\x{123}
 
+# This tests processing wide characters in extended mode.
+
+/XȀ/x,utf
+
 # End of testinput5