diff --git a/include/m_ctype.h b/include/m_ctype.h
index 81096f60c78..87b1e529f65 100644
--- a/include/m_ctype.h
+++ b/include/m_ctype.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -33,11 +33,11 @@ extern "C" {
 #define MY_CS_TO_UPPER_TABLE_SIZE	256
 #define MY_CS_SORT_ORDER_TABLE_SIZE	256
 #define MY_CS_TO_UNI_TABLE_SIZE		256
-
 #define CHARSET_DIR	"charsets/"
 
 #define my_wc_t ulong
 
+#define MY_CS_MAX_CHAR 0xFFFF
 #define MY_CS_REPLACEMENT_CHARACTER 0xFFFD
 
 /*
diff --git a/strings/ctype-ucs2.c b/strings/ctype-ucs2.c
index 37fd1b5349f..f1beff82a40 100644
--- a/strings/ctype-ucs2.c
+++ b/strings/ctype-ucs2.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2003, 2016, Oracle and/or its affiliates. All rights reserved.
    
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ -1099,7 +1099,7 @@ static inline void
 my_tolower_utf16(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256 && uni_plane[page])
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR && uni_plane[page])
     *wc= uni_plane[page][*wc & 0xFF].tolower;
 }
 
@@ -1108,7 +1108,7 @@ static inline void
 my_toupper_utf16(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256 && uni_plane[page])
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR && uni_plane[page])
     *wc= uni_plane[page][*wc & 0xFF].toupper;
 }
 
@@ -1117,7 +1117,7 @@ static inline void
 my_tosort_utf16(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256)
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR)
   {
     if (uni_plane[page])
       *wc= uni_plane[page][*wc & 0xFF].sort;
@@ -1728,7 +1728,7 @@ static inline void
 my_tolower_utf32(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256 && uni_plane[page])
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR && uni_plane[page])
     *wc= uni_plane[page][*wc & 0xFF].tolower;
 }
 
@@ -1737,7 +1737,7 @@ static inline void
 my_toupper_utf32(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256 && uni_plane[page])
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR && uni_plane[page])
     *wc= uni_plane[page][*wc & 0xFF].toupper;
 }
 
@@ -1746,7 +1746,7 @@ static inline void
 my_tosort_utf32(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256)
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR)
   {
     if (uni_plane[page])
       *wc= uni_plane[page][*wc & 0xFF].sort;
diff --git a/strings/ctype-utf8.c b/strings/ctype-utf8.c
index 52e05f17d61..33e5703ffd9 100644
--- a/strings/ctype-utf8.c
+++ b/strings/ctype-utf8.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ -1941,7 +1941,7 @@ static inline void
 my_tosort_unicode(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256)
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR)
   {
     if (uni_plane[page])
       *wc= uni_plane[page][*wc & 0xFF].sort;
@@ -5023,7 +5023,7 @@ static inline void
 my_tolower_utf8mb4(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256 && uni_plane[page])
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR && uni_plane[page])
     *wc= uni_plane[page][*wc & 0xFF].tolower;
 }
 
@@ -5032,7 +5032,7 @@ static inline void
 my_toupper_utf8mb4(MY_UNICASE_INFO **uni_plane, my_wc_t *wc)
 {
   int page= *wc >> 8;
-  if (page < 256 && uni_plane[page])
+  if (page < 256 && *wc <= MY_CS_MAX_CHAR && uni_plane[page])
     *wc= uni_plane[page][*wc & 0xFF].toupper;
 }