diff --git a/gobex/gobex-header.c b/gobex/gobex-header.c
index a21362c..1e5e534 100644
--- a/gobex/gobex-header.c
+++ b/gobex/gobex-header.c
return header;
}
-GObexHeader *g_obex_header_new_bytes(guint8 id, void *data, gsize len)
+GObexHeader *g_obex_header_new_bytes(guint8 id, const void *data, gsize len)
{
GObexHeader *header;
diff --git a/gobex/gobex-header.h b/gobex/gobex-header.h
index 9a8dd03..721fc36 100644
--- a/gobex/gobex-header.h
+++ b/gobex/gobex-header.h
gboolean g_obex_header_get_uint32(GObexHeader *header, guint32 *val);
GObexHeader *g_obex_header_new_unicode(guint8 id, const char *str);
-GObexHeader *g_obex_header_new_bytes(guint8 id, void *data, gsize len);
+GObexHeader *g_obex_header_new_bytes(guint8 id, const void *data, gsize len);
GObexHeader *g_obex_header_new_uint8(guint8 id, guint8 val);
GObexHeader *g_obex_header_new_uint32(guint8 id, guint32 val);