diff --git a/apps/plugins/viewer.c b/apps/plugins/viewer.c
old mode 100644
new mode 100755
index 7e03c55..0f04513
--- a/apps/plugins/viewer.c
+++ b/apps/plugins/viewer.c
@@ -422,6 +422,9 @@ static unsigned char *next_line_ptr;
 static struct font *pf;
 #endif
 
+/* UTF-8 BOM */
+#define BOM "\xef\xbb\xbf"
+#define BOM_SIZE 3
 
 int glyph_width(int ch)
 {
@@ -715,9 +718,22 @@ static void fill_buffer(long pos, unsigned char* buf, unsigned size)
     /* To minimize disk access, always read on sector boundaries */
     unsigned numread, i;
     bool found_CR = false;
+    off_t offset = rb->lseek(fd, pos, SEEK_SET);
+
+    if (offset == 0 && prefs.encoding == UTF_8)
+    {
+        /* check BOM */
+        unsigned char bom[BOM_SIZE];
+
+        if (rb->read(fd, bom, BOM_SIZE) == BOM_SIZE)
+        {
+            if (memcmp(bom, BOM, BOM_SIZE))
+                rb->lseek(fd, 0, SEEK_SET);
+        }
+    }
 
-    rb->lseek(fd, pos, SEEK_SET);
     numread = rb->read(fd, buf, size);
+    buf[numread] = 0;
     rb->button_clear_queue(); /* clear button queue */
 
     for(i = 0; i < numread; i++) {
@@ -1156,16 +1172,39 @@ static bool viewer_init(void)
     if (fd==-1)
         return false;
 
-    file_size = rb->filesize(fd);
-    if (file_size==-1)
-        return false;
-
     /* Init mac_text value used in processing buffer */
     mac_text = false;
 
     return true;
 }
 
+/* When a file is UTF-8 file with BOM, if prefs.encoding is UTF-8,
+ * then file size decreases only BOM_SIZE.
+ */
+static void get_filesize(void)
+{
+    file_size = rb->filesize(fd);
+    if (file_size==-1)
+        return;
+
+    if (prefs.encoding == UTF_8)
+    {
+        /* check BOM */
+        unsigned char bom[BOM_SIZE];
+        off_t cur = rb->lseek(fd, 0, SEEK_CUR);
+
+        if (cur != 0)
+            rb->lseek(fd, 0, SEEK_SET);
+
+        if (rb->read(fd, bom, BOM_SIZE) == BOM_SIZE)
+        {
+            if (!memcmp(bom, BOM, BOM_SIZE))
+                file_size -= BOM_SIZE;
+        }
+        rb->lseek(fd, cur, SEEK_SET);
+    }
+}
+
 static void viewer_default_settings(void)
 {
     prefs.word_mode = WRAP;
@@ -1202,6 +1241,8 @@ static void viewer_load_settings(void) /* same name as global, but not the same
 
     rb->memcpy(&old_prefs, &prefs, sizeof(struct preferences));
 
+    get_filesize();
+
     data = (struct bookmark_file_data*)buffer; /* grab the text buffer */
     data->bookmarked_files_count = 0;
 
@@ -1341,6 +1382,8 @@ static bool encoding_setting(void)
 {
     static struct opt_items names[NUM_CODEPAGES];
     int idx;
+    bool res;
+    enum codepages oldenc = prefs.encoding;
 
     for (idx = 0; idx < NUM_CODEPAGES; idx++)
     {
@@ -1348,8 +1391,20 @@ static bool encoding_setting(void)
         names[idx].voice_id = -1;
     }
 
-    return rb->set_option("Encoding", &prefs.encoding, INT, names,
+    res = rb->set_option("Encoding", &prefs.encoding, INT, names,
                           sizeof(names) / sizeof(names[0]), NULL);
+
+    /* When prefs.encoding changes into UTF-8 or changes from UTF-8,
+     * filesize (file_size) might change.
+     * In addition, if prefs.encoding is UTF-8, then BOM does not read.
+     */
+    if (oldenc != prefs.encoding && (oldenc == UTF_8 || prefs.encoding == UTF_8))
+    {
+        get_filesize();
+        fill_buffer(file_pos, buffer, buffer_size);
+    }
+
+    return res;
 }
 
 static bool word_wrap_setting(void)