diff --git a/bin/xbps-install/defs.h b/bin/xbps-install/defs.h
index dbd4f7a5..3a9b7188 100644
--- a/bin/xbps-install/defs.h
+++ b/bin/xbps-install/defs.h
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2009-2013 Juan Romero Pardines.
+ * Copyright (c) 2009-2014 Juan Romero Pardines.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -45,10 +45,10 @@ bool	yesno(const char *, ...);
 bool	noyes(const char *, ...);
 
 /* from fetch_cb.c */
-void	fetch_file_progress_cb(struct xbps_fetch_cb_data *, void *);
+void	fetch_file_progress_cb(const struct xbps_fetch_cb_data *, void *);
 
 /* from state_cb.c */
-int	state_cb(struct xbps_state_cb_data *, void *);
+int	state_cb(const struct xbps_state_cb_data *, void *);
 
 /* From util.c */
 void	print_package_line(const char *, int, bool);
diff --git a/bin/xbps-install/fetch_cb.c b/bin/xbps-install/fetch_cb.c
index 162fcf76..6c0ac05f 100644
--- a/bin/xbps-install/fetch_cb.c
+++ b/bin/xbps-install/fetch_cb.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2009-2012 Juan Romero Pardines
+ * Copyright (c) 2009-2014 Juan Romero Pardines
  * Copyright (c) 2000-2004 Dag-Erling Coïdan Smørgrav
  * All rights reserved.
  *
@@ -60,7 +60,7 @@ get_time(struct timeval *tvp)
  * Compute and display ETA
  */
 static const char *
-stat_eta(struct xbps_fetch_cb_data *xfpd, void *cbdata)
+stat_eta(const struct xbps_fetch_cb_data *xfpd, void *cbdata)
 {
 	struct xferstat *xfer = cbdata;
 	static char str[16];
@@ -99,7 +99,7 @@ compare_double(const double a, const double b)
  * Compute and display transfer rate
  */
 static const char *
-stat_bps(struct xbps_fetch_cb_data *xfpd, void *cbdata)
+stat_bps(const struct xbps_fetch_cb_data *xfpd, void *cbdata)
 {
 	struct xferstat *xfer = cbdata;
 	static char str[16];
@@ -122,7 +122,7 @@ stat_bps(struct xbps_fetch_cb_data *xfpd, void *cbdata)
  * Update the stats display
  */
 static void
-stat_display(struct xbps_fetch_cb_data *xfpd, void *cbdata)
+stat_display(const struct xbps_fetch_cb_data *xfpd, void *cbdata)
 {
 	struct xferstat *xfer = cbdata;
 	struct timeval now;
@@ -153,7 +153,7 @@ stat_display(struct xbps_fetch_cb_data *xfpd, void *cbdata)
 }
 
 void
-fetch_file_progress_cb(struct xbps_fetch_cb_data *xfpd, void *cbdata)
+fetch_file_progress_cb(const struct xbps_fetch_cb_data *xfpd, void *cbdata)
 {
 	struct xferstat *xfer = cbdata;
 	char size[8];
diff --git a/bin/xbps-install/main.c b/bin/xbps-install/main.c
index 20c01886..67efeae3 100644
--- a/bin/xbps-install/main.c
+++ b/bin/xbps-install/main.c
@@ -64,7 +64,7 @@ usage(bool fail)
 }
 
 static void
-unpack_progress_cb(struct xbps_unpack_cb_data *xpd, void *cbdata _unused)
+unpack_progress_cb(const struct xbps_unpack_cb_data *xpd, void *cbdata _unused)
 {
 	if (xpd->entry == NULL || xpd->entry_total_count <= 0)
 		return;
diff --git a/bin/xbps-install/state_cb.c b/bin/xbps-install/state_cb.c
index 5e63e766..dffbf5e1 100644
--- a/bin/xbps-install/state_cb.c
+++ b/bin/xbps-install/state_cb.c
@@ -32,7 +32,7 @@
 #include "defs.h"
 
 int
-state_cb(struct xbps_state_cb_data *xscd, void *cbdata _unused)
+state_cb(const struct xbps_state_cb_data *xscd, void *cbdata _unused)
 {
 	xbps_dictionary_t pkgd;
 	const char *instver, *newver;
diff --git a/bin/xbps-reconfigure/main.c b/bin/xbps-reconfigure/main.c
index dcc944b7..cbb37ed0 100644
--- a/bin/xbps-reconfigure/main.c
+++ b/bin/xbps-reconfigure/main.c
@@ -51,7 +51,7 @@ usage(bool fail)
 }
 
 static int
-state_cb(struct xbps_state_cb_data *xscd, void *cbd _unused)
+state_cb(const struct xbps_state_cb_data *xscd, void *cbd _unused)
 {
 	bool slog = false;
 
diff --git a/bin/xbps-remove/main.c b/bin/xbps-remove/main.c
index d5808f2d..5c2f23ae 100644
--- a/bin/xbps-remove/main.c
+++ b/bin/xbps-remove/main.c
@@ -63,7 +63,7 @@ usage(bool fail)
 }
 
 static int
-state_cb_rm(struct xbps_state_cb_data *xscd, void *cbdata _unused)
+state_cb_rm(const struct xbps_state_cb_data *xscd, void *cbdata _unused)
 {
 	bool slog = false;
 
diff --git a/include/xbps.h.in b/include/xbps.h.in
index ab20f018..b93317b3 100644
--- a/include/xbps.h.in
+++ b/include/xbps.h.in
@@ -48,7 +48,7 @@
  *
  * This header documents the full API for the XBPS Library.
  */
-#define XBPS_API_VERSION	"20140905"
+#define XBPS_API_VERSION	"20140906"
 
 #ifndef XBPS_VERSION
  #define XBPS_VERSION		"UNSET"
@@ -538,7 +538,7 @@ struct xbps_handle {
 	 * Pointer to the supplifed function callback to be used
 	 * in the XBPS possible states.
 	 */
-	int (*state_cb)(struct xbps_state_cb_data *, void *);
+	int (*state_cb)(const struct xbps_state_cb_data *, void *);
 	/**
 	 * @var state_cb_data
 	 *
@@ -550,7 +550,7 @@ struct xbps_handle {
 	 * Pointer to the supplied function callback to be used in
 	 * xbps_unpack_binary_pkg().
 	 */
-	void (*unpack_cb)(struct xbps_unpack_cb_data *, void *);
+	void (*unpack_cb)(const struct xbps_unpack_cb_data *, void *);
 	/**
 	 * @var unpack_cb_data
 	 *
@@ -562,7 +562,7 @@ struct xbps_handle {
 	 * Pointer to the supplied function callback to be used in
 	 * xbps_fetch_file().
 	 */
-	void (*fetch_cb)(struct xbps_fetch_cb_data *, void *);
+	void (*fetch_cb)(const struct xbps_fetch_cb_data *, void *);
 	/**
 	 * @var fetch_cb_data
 	 *