diff --git a/src/library/codestream.c b/src/library/codestream.c
index ca96310..d1c7dee 100755
--- a/src/library/codestream.c
+++ b/src/library/codestream.c
@@ -637,7 +637,7 @@ parse_main_header(bwc_data *const data,bitstream *const stream)
             info->precision = codec_prec =  (uint8)get_symbol(stream,  1);
 
             buffer_char       =  (char*)get_chunck(stream, 10);
-            strncpy(info->f_ext, buffer_char, sizeof(buffer_char)/sizeof(*buffer_char));
+            strncpy(info->f_ext, buffer_char, 10);
             free(buffer_char);
 
             for(p = 0; p < nPar; ++p)
@@ -1783,4 +1783,4 @@ parse_codestream(bwc_data *const data, uint8 const layer)
    free(stream);
 
    return field;
-}
\ No newline at end of file
+}