diff --git a/src/expand-common.c b/src/expand-common.c

index 4657e46..97cbb09 100644

--- a/src/expand-common.c

+++ b/src/expand-common.c

@@ -18,6 +18,7 @@

 #include <stdio.h>

 #include <sys/types.h>

+#include <mbfile.h>

 #include "system.h"

 #include "die.h"

 #include "error.h"

@@ -85,6 +86,119 @@ add_tab_stop (uintmax_t tabval)

     }

 }

+extern int

+set_utf_locale (void)

+{

+      /*try using some predefined locale */

+      const char* predef_locales[] = {"C.UTF8","en_US.UTF8","en_GB.UTF8"};

+

+      const int predef_locales_count=3;

+      for (int i=0;i

+        {

+          if (setlocale(LC_ALL,predef_locales[i])!=NULL)

+          {

+            break;

+          }

+          else if (i==predef_locales_count-1)

+          {

+            return 1;

+            error (EXIT_FAILURE, errno, _("cannot set UTF-8 locale"));

+          }

+        }

+        return 0;

+}

+

+extern bool

+check_utf_locale(void)

+{

+  char* locale = setlocale (LC_CTYPE , NULL);

+  if (locale == NULL) 

+  {

+    return false;

+  }

+  else if (strcasestr(locale, "utf8") == NULL && strcasestr(locale, "utf-8") == NULL)

+  { 

+    return false;

+  }

+  return true;

+}

+

+extern bool

+check_bom(FILE* fp, mb_file_t *mbf)

+{

+  int c;

+

+

+  c=fgetc(fp);

+

+  /*test BOM header of the first file */

+  mbf->bufcount=0;

+  if (c == 0xEF)

+  {

+    c=fgetc(fp);

+  }

+  else

+  {

+    if (c != EOF)

+    {

+      ungetc(c,fp);

+    }

+    return false;

+  }

+

+  if (c == 0xBB)

+  {

+    c=fgetc(fp);

+  }

+  else

+  {

+    if ( c!= EOF )

+    {

+      mbf->buf[0]=(unsigned char) 0xEF;

+      mbf->bufcount=1;

+      ungetc(c,fp);

+      return false;

+    }

+    else

+    {

+      ungetc(0xEF,fp);

+      return false;

+    }

+  }

+  if (c == 0xBF)

+  {

+    mbf->bufcount=0;

+    return true;

+  }

+  else

+  {

+    if (c != EOF)

+    {

+      mbf->buf[0]=(unsigned char) 0xEF;

+      mbf->buf[1]=(unsigned char) 0xBB;

+      mbf->bufcount=2;

+      ungetc(c,fp);

+      return false;

+    }

+    else

+    {

+      mbf->buf[0]=(unsigned char) 0xEF;

+      mbf->bufcount=1;

+      ungetc(0xBB,fp);

+      return false;

+    }

+  }

+  return false;

+}

+

+extern void

+print_bom(void)

+{

+  putc (0xEF, stdout);

+  putc (0xBB, stdout);

+  putc (0xBF, stdout);

+}

+

 /* Add the comma or blank separated list of tab stops STOPS

    to the list of tab stops.  */

 extern void

diff --git a/src/expand-common.h b/src/expand-common.h

index 8cb2079..763bfda 100644

--- a/src/expand-common.h

+++ b/src/expand-common.h

@@ -34,6 +34,18 @@ extern size_t max_column_width;

 /* The desired exit status.  */

 extern int exit_status;

+extern int

+set_utf_locale (void);

+

+extern bool

+check_utf_locale(void);

+

+extern bool

+check_bom(FILE* fp, mb_file_t *mbf);

+

+extern void 

+print_bom(void);

+

 /* Add tab stop TABVAL to the end of 'tab_list'.  */

 extern void

 add_tab_stop (uintmax_t tabval);

diff --git a/src/expand.c b/src/expand.c

index 310b349..4136824 100644

--- a/src/expand.c

+++ b/src/expand.c

@@ -105,11 +105,33 @@ expand (void)

   FILE *fp = next_file (NULL);

   mb_file_t mbf;

   mbf_char_t c;

-

+  /* True if the starting locale is utf8.  */

+  bool using_utf_locale;

+ 

+  /* True if the first file contains BOM header.  */

+  bool found_bom;

+  using_utf_locale=check_utf_locale();

+  

   if (!fp)

     return;

-

   mbf_init (mbf, fp);

+  found_bom=check_bom(fp,&mbf);

+

+  if (using_utf_locale == false && found_bom == true)

+  {

+    /*try using some predefined locale */

+    

+    if (set_utf_locale () != 0)

+    {

+      error (EXIT_FAILURE, errno, _("cannot set UTF-8 locale"));

+    }

+  }

+ 

+

+  if (found_bom == true)

+  {

+    print_bom();

+  }

   while (true)

     {

@@ -134,6 +156,27 @@ expand (void)

             if ((mb_iseof (c)) && (fp = next_file (fp)))

               {

                 mbf_init (mbf, fp);

+                if (fp!=NULL)

+                {

+                  if (check_bom(fp,&mbf)==true)

+                  {

+                    /*Not the first file - check BOM header*/

+                    if (using_utf_locale==false && found_bom==false)

+                    {

+                      /*BOM header in subsequent file but not in the first one. */

+                      error (EXIT_FAILURE, errno, _("combination of files with and without BOM header"));

+                    }

+                  }

+                  else

+                  {

+                    if(using_utf_locale==false && found_bom==true)

+                    {

+                      /*First file conatined BOM header - locale was switched to UTF 

+                      /*all subsequent files should contain BOM. */

+                      error (EXIT_FAILURE, errno, _("combination of files with and without BOM header"));

+                    }

+                  }

+                }

                 continue;

               }

             else

diff --git a/src/unexpand.c b/src/unexpand.c

index 863a90a..5681b58 100644

--- a/src/unexpand.c

+++ b/src/unexpand.c

@@ -116,16 +116,36 @@ unexpand (void)

      include characters other than spaces, so the blanks must be

      stored, not merely counted.  */

   mbf_char_t *pending_blank;

+  /* True if the starting locale is utf8.  */

+  bool using_utf_locale;

+ 

+  /* True if the first file contains BOM header.  */

+  bool found_bom;

+  using_utf_locale=check_utf_locale();

   if (!fp)

     return;

+  mbf_init (mbf, fp);

+  found_bom=check_bom(fp,&mbf);

+  if (using_utf_locale == false && found_bom == true)

+  {

+    /*try using some predefined locale */

+    

+    if (set_utf_locale () != 0)

+    {

+      error (EXIT_FAILURE, errno, _("cannot set UTF-8 locale"));

+    }

+  }

   /* The worst case is a non-blank character, then one blank, then a

      tab stop, then MAX_COLUMN_WIDTH - 1 blanks, then a non-blank; so

      allocate MAX_COLUMN_WIDTH bytes to store the blanks.  */

   pending_blank = xmalloc (max_column_width * sizeof (mbf_char_t));

-  mbf_init (mbf, fp);

+  if (found_bom == true)

+  {

+    print_bom();

+  }

   while (true)

     {

@@ -169,6 +189,27 @@ unexpand (void)

             if ((mb_iseof (c)) && (fp = next_file (fp)))

               {

                 mbf_init (mbf, fp);

+                if (fp!=NULL)

+                {

+                  if (check_bom(fp,&mbf)==true)

+                  {

+                    /*Not the first file - check BOM header*/

+                    if (using_utf_locale==false && found_bom==false)

+                    {

+                      /*BOM header in subsequent file but not in the first one. */

+                      error (EXIT_FAILURE, errno, _("combination of files with and without BOM header"));

+                    }

+                  }

+                  else

+                  {

+                    if(using_utf_locale==false && found_bom==true)

+                    {

+                      /*First file conatined BOM header - locale was switched to UTF 

+                      /*all subsequent files should contain BOM. */

+                      error (EXIT_FAILURE, errno, _("combination of files with and without BOM header"));

+                    }

+                  }

+                }

                 continue;

               }

             else

diff --git a/tests/expand/mb.sh b/tests/expand/mb.sh

index 031be7a..1621c84 100755

--- a/tests/expand/mb.sh

+++ b/tests/expand/mb.sh

@@ -109,4 +109,75 @@ env printf '12345678

 expand < in > out || fail=1

 compare exp out > /dev/null 2>&1 || fail=1

+

+

+#BOM header test 1 

+printf "\xEF\xBB\xBF" > in; cat <<\EOF >> in || framework_failure_

+1234567812345678123456781

+.       .       .       .

+a	b	c	d

+.       .       .       .

+ä	ö	ü	ß

+.       .       .       .

+EOF

+env printf '   äöü\t.    öüä.   \tä xx\n' >> in || framework_failure_

+

+printf "\xEF\xBB\xBF" > exp; cat <<\EOF >> exp || framework_failure_

+1234567812345678123456781

+.       .       .       .

+a       b       c       d

+.       .       .       .

+ä       ö       ü       ß

+.       .       .       .

+   äöü  .    öüä.       ä xx

+EOF

+

+

+expand < in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LANG=C expand < in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LC_ALL=C expand < in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+

+printf '\xEF\xBB\xBF' > in1; cat <<\EOF >> in1 || framework_failure_

+1234567812345678123456781

+.       .       .       .

+a	b	c	d

+.       .       .       .

+ä	ö	ü	ß

+.       .       .       .

+EOF

+env printf '   äöü\t.    öüä.   \tä xx\n' >> in1 || framework_failure_

+

+

+printf '\xEF\xBB\xBF' > exp; cat <<\EOF >> exp || framework_failure_

+1234567812345678123456781

+.       .       .       .

+a       b       c       d

+.       .       .       .

+ä       ö       ü       ß

+.       .       .       .

+   äöü  .    öüä.       ä xx

+1234567812345678123456781

+.       .       .       .

+a       b       c       d

+.       .       .       .

+ä       ö       ü       ß

+.       .       .       .

+   äöü  .    öüä.       ä xx

+EOF

+

+expand in1 in1 > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LANG=C expand in1 in1  > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LC_ALL=C expand in1 in1 > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

 exit $fail

diff --git a/tests/unexpand/mb.sh b/tests/unexpand/mb.sh

index 8d75652..9d4ee3e 100755

--- a/tests/unexpand/mb.sh

+++ b/tests/unexpand/mb.sh

@@ -111,3 +111,62 @@ env printf '12345678

 unexpand -a < in > out || fail=1

 compare exp out > /dev/null 2>&1 || fail=1

+

+#BOM header test 1 

+printf "\xEF\xBB\xBF" > in; cat <<\EOF >> in || framework_failure_

+1234567812345678123456781

+.       .       .       .

+a       b       c       d

+.       .       .       .

+ä       ö       ü       ß

+.       .       .       .

+   äöü  .    öüä.       ä xx

+EOF

+env printf '   äöü\t.    öüä.   \tä xx\n' >> in || framework_failure_

+

+printf "\xEF\xBB\xBF" > exp; cat <<\EOF >> exp || framework_failure_

+1234567812345678123456781

+.	.	.	.

+a	b	c	d

+.	.	.	.

+ä	ö	ü	ß

+.	.	.	.

+   äöü	.    öüä.	ä xx

+EOF

+

+unexpand < in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LANG=C unexpand < in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LC_ALL=C unexpand < in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+

+printf "\xEF\xBB\xBF" > exp; cat <<\EOF >> exp || framework_failure_

+1234567812345678123456781

+.	.	.	.

+a	b	c	d

+.	.	.	.

+ä	ö	ü	ß

+.	.	.	.

+   äöü	.    öüä.	ä xx

+1234567812345678123456781

+.	.	.	.

+a	b	c	d

+.	.	.	.

+ä	ö	ü	ß

+.	.	.	.

+   äöü	.    öüä.	ä xx

+EOF

+

+

+unexpand in in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LANG=C unexpand in in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1

+

+LC_ALL=C unexpand in in > out || fail=1

+compare exp out > /dev/null 2>&1 || fail=1