diff --git a/ChangeLog b/ChangeLog
index aaede8836f..a831b6a3c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2006-03-11  Sven Neumann  <sven@gimp.org>
+
+	* libgimpbase/gimpwire.h: added a const qualifier to the
+	GimpWireIOFunc signature.
+
+	* libgimp/gimp.c (gimp_write)
+	* app/plug-in/plug-in.c (plug_in_write): changed accordingly.
+
 2006-03-10  Sven Neumann  <ven@gimp.org>
 
 	* app/widgets/gimpaction.c: factored out some code to a utility
diff --git a/app/plug-in/gimpplugin.c b/app/plug-in/gimpplugin.c
index 75125839fa..1922474e5a 100644
--- a/app/plug-in/gimpplugin.c
+++ b/app/plug-in/gimpplugin.c
@@ -92,7 +92,7 @@
 /*  local funcion prototypes  */
 
 static gboolean   plug_in_write         (GIOChannel   *channel,
-                                         guint8       *buf,
+                                         const guint8 *buf,
                                          gulong        count,
                                          gpointer      user_data);
 static gboolean   plug_in_flush         (GIOChannel   *channel,
@@ -144,9 +144,7 @@ plug_in_exit (Gimp *gimp)
   list = gimp->open_plug_ins;
   while (list)
     {
-      PlugIn *plug_in;
-
-      plug_in = (PlugIn *) list->data;
+      PlugIn *plug_in = list->data;
 
       list = list->next;
 
@@ -766,10 +764,10 @@ plug_in_recv_message (GIOChannel   *channel,
 }
 
 static gboolean
-plug_in_write (GIOChannel *channel,
-	       guint8     *buf,
-	       gulong      count,
-               gpointer    user_data)
+plug_in_write (GIOChannel   *channel,
+	       const guint8 *buf,
+	       gulong        count,
+               gpointer      user_data)
 {
   PlugIn *plug_in = user_data;
   gulong  bytes;
diff --git a/app/plug-in/plug-in.c b/app/plug-in/plug-in.c
index 75125839fa..1922474e5a 100644
--- a/app/plug-in/plug-in.c
+++ b/app/plug-in/plug-in.c
@@ -92,7 +92,7 @@
 /*  local funcion prototypes  */
 
 static gboolean   plug_in_write         (GIOChannel   *channel,
-                                         guint8       *buf,
+                                         const guint8 *buf,
                                          gulong        count,
                                          gpointer      user_data);
 static gboolean   plug_in_flush         (GIOChannel   *channel,
@@ -144,9 +144,7 @@ plug_in_exit (Gimp *gimp)
   list = gimp->open_plug_ins;
   while (list)
     {
-      PlugIn *plug_in;
-
-      plug_in = (PlugIn *) list->data;
+      PlugIn *plug_in = list->data;
 
       list = list->next;
 
@@ -766,10 +764,10 @@ plug_in_recv_message (GIOChannel   *channel,
 }
 
 static gboolean
-plug_in_write (GIOChannel *channel,
-	       guint8     *buf,
-	       gulong      count,
-               gpointer    user_data)
+plug_in_write (GIOChannel   *channel,
+	       const guint8 *buf,
+	       gulong        count,
+               gpointer      user_data)
 {
   PlugIn *plug_in = user_data;
   gulong  bytes;
diff --git a/libgimp/gimp.c b/libgimp/gimp.c
index a261a1d817..1f9f3f187a 100644
--- a/libgimp/gimp.c
+++ b/libgimp/gimp.c
@@ -142,7 +142,7 @@ static gboolean   gimp_plugin_io_error_handler (GIOChannel      *channel,
                                                 GIOCondition     cond,
                                                 gpointer         data);
 static gboolean   gimp_write                   (GIOChannel      *channel,
-                                                guint8          *buf,
+                                                const guint8    *buf,
                                                 gulong           count,
                                                 gpointer         user_data);
 static gboolean   gimp_flush                   (GIOChannel      *channel,
@@ -1520,10 +1520,10 @@ gimp_plugin_io_error_handler (GIOChannel   *channel,
 }
 
 static gboolean
-gimp_write (GIOChannel *channel,
-            guint8     *buf,
-            gulong      count,
-            gpointer    user_data)
+gimp_write (GIOChannel   *channel,
+            const guint8 *buf,
+            gulong        count,
+            gpointer      user_data)
 {
   gulong bytes;
 
diff --git a/libgimpbase/gimpwire.h b/libgimpbase/gimpwire.h
index f7bfdae430..4a96beaa26 100644
--- a/libgimpbase/gimpwire.h
+++ b/libgimpbase/gimpwire.h
@@ -35,7 +35,7 @@ typedef void     (* GimpWireWriteFunc)   (GIOChannel      *channel,
                                           gpointer         user_data);
 typedef void     (* GimpWireDestroyFunc) (GimpWireMessage *msg);
 typedef gboolean (* GimpWireIOFunc)      (GIOChannel      *channel,
-                                          guint8          *buf,
+                                          const guint8    *buf,
                                           gulong           count,
                                           gpointer         user_data);
 typedef gboolean (* GimpWireFlushFunc)   (GIOChannel      *channel,