diff --git a/doc/en/weechat_plugin_api.en.txt b/doc/en/weechat_plugin_api.en.txt
index 440317fdb..3ee15b6a4 100644
--- a/doc/en/weechat_plugin_api.en.txt
+++ b/doc/en/weechat_plugin_api.en.txt
@@ -2883,8 +2883,8 @@ Prototype:
 [source,C]
 ----------------------------------------
 int weechat_hashtable_set_with_size (struct t_hashtable *hashtable,
-                                     void *key, int key_size,
-                                     void *value, int value_size);
+                                     const void *key, int key_size,
+                                     const void *value, int value_size);
 ----------------------------------------
 
 Arguments:
@@ -2924,7 +2924,7 @@ Prototype:
 [source,C]
 ----------------------------------------
 int weechat_hashtable_set (struct t_hashtable *hashtable,
-                           void *key, void *value);
+                           const void *key, const void *value);
 ----------------------------------------
 
 Arguments:
diff --git a/doc/fr/weechat_plugin_api.fr.txt b/doc/fr/weechat_plugin_api.fr.txt
index 18cf35346..b78020fb4 100644
--- a/doc/fr/weechat_plugin_api.fr.txt
+++ b/doc/fr/weechat_plugin_api.fr.txt
@@ -2914,8 +2914,8 @@ Prototype :
 [source,C]
 ----------------------------------------
 int weechat_hashtable_set_with_size (struct t_hashtable *hashtable,
-                                     void *key, int key_size,
-                                     void *value, int value_size);
+                                     const void *key, int key_size,
+                                     const void *value, int value_size);
 ----------------------------------------
 
 Paramètres :
@@ -2955,7 +2955,7 @@ Prototype :
 [source,C]
 ----------------------------------------
 int weechat_hashtable_set (struct t_hashtable *hashtable,
-                           void *key, void *value);
+                           const void *key, const void *value);
 ----------------------------------------
 
 Paramètres :
diff --git a/doc/it/weechat_plugin_api.it.txt b/doc/it/weechat_plugin_api.it.txt
index 1ccd4d5c9..cd7b45bf8 100644
--- a/doc/it/weechat_plugin_api.it.txt
+++ b/doc/it/weechat_plugin_api.it.txt
@@ -2919,8 +2919,8 @@ Prototipo:
 [source,C]
 ----------------------------------------
 int weechat_hashtable_set_with_size (struct t_hashtable *hashtable,
-                                     void *key, int key_size,
-                                     void *value, int value_size);
+                                     const void *key, int key_size,
+                                     const void *value, int value_size);
 ----------------------------------------
 
 Arguments:
@@ -2960,7 +2960,7 @@ Prototipo:
 [source,C]
 ----------------------------------------
 int weechat_hashtable_set (struct t_hashtable *hashtable,
-                           void *key, void *value);
+                           const void *key, const void *value);
 ----------------------------------------
 
 Argomenti:
diff --git a/src/core/wee-hashtable.c b/src/core/wee-hashtable.c
index 4575f3d95..f11e7672c 100644
--- a/src/core/wee-hashtable.c
+++ b/src/core/wee-hashtable.c
@@ -158,7 +158,8 @@ hashtable_new (int size,
  */
 
 void
-hashtable_alloc_type (enum t_hashtable_type type, void *value, int size_value,
+hashtable_alloc_type (enum t_hashtable_type type,
+                      const void *value, int size_value,
                       void **pointer, int *size)
 {
     switch (type)
@@ -179,7 +180,7 @@ hashtable_alloc_type (enum t_hashtable_type type, void *value, int size_value,
             *size = (*pointer) ? strlen (*pointer) + 1 : 0;
             break;
         case HASHTABLE_POINTER:
-            *pointer = value;
+            *pointer = (void *)value;
             *size = sizeof (void *);
             break;
         case HASHTABLE_BUFFER:
@@ -239,8 +240,8 @@ hashtable_free_type (enum t_hashtable_type type, void *value)
 
 int
 hashtable_set_with_size (struct t_hashtable *hashtable,
-                         void *key, int key_size,
-                         void *value, int value_size)
+                         const void *key, int key_size,
+                         const void *value, int value_size)
 {
     unsigned int hash;
     struct t_hashtable_item *ptr_item, *pos_item, *new_item;
@@ -319,7 +320,8 @@ hashtable_set_with_size (struct t_hashtable *hashtable,
  */
 
 int
-hashtable_set (struct t_hashtable *hashtable, void *key, void *value)
+hashtable_set (struct t_hashtable *hashtable,
+               const void *key, const void *value)
 {
     return hashtable_set_with_size (hashtable, key, 0, value, 0);
 }
diff --git a/src/core/wee-hashtable.h b/src/core/wee-hashtable.h
index fbc06eb66..baad83773 100644
--- a/src/core/wee-hashtable.h
+++ b/src/core/wee-hashtable.h
@@ -109,10 +109,10 @@ extern struct t_hashtable *hashtable_new (int size,
                                           t_hashtable_hash_key *hash_key_cb,
                                           t_hashtable_keycmp *keycmp_cb);
 extern int hashtable_set_with_size (struct t_hashtable *hashtable,
-                                    void *key, int key_size,
-                                    void *value, int value_size);
-extern int hashtable_set (struct t_hashtable *hashtable, void *key,
-                          void *value);
+                                    const void *key, int key_size,
+                                    const void *value, int value_size);
+extern int hashtable_set (struct t_hashtable *hashtable, const void *key,
+                          const void *value);
 extern void *hashtable_get (struct t_hashtable *hashtable, const void *key);
 extern int hashtable_has_key (struct t_hashtable *hashtable, const void *key);
 extern void hashtable_map (struct t_hashtable *hashtable,
diff --git a/src/gui/gui-buffer.c b/src/gui/gui-buffer.c
index f62fc4b2c..bf742b5a7 100644
--- a/src/gui/gui-buffer.c
+++ b/src/gui/gui-buffer.c
@@ -140,8 +140,7 @@ gui_buffer_local_var_add (struct t_gui_buffer *buffer, const char *name,
         return;
     
     ptr_value = hashtable_get (buffer->local_variables, name);
-    hashtable_set (buffer->local_variables,
-                   (void *)name, (void *)value);
+    hashtable_set (buffer->local_variables, name, value);
     hook_signal_send ((ptr_value) ?
                       "buffer_localvar_changed" : "buffer_localvar_added",
                       WEECHAT_HOOK_SIGNAL_POINTER, buffer);
@@ -478,9 +477,8 @@ gui_buffer_new (struct t_weechat_plugin *plugin,
                                                      NULL,
                                                      NULL);
         hashtable_set (new_buffer->local_variables,
-                       "plugin", (void *)plugin_get_name (plugin));
-        hashtable_set (new_buffer->local_variables,
-                       "name", (void *)name);
+                       "plugin", plugin_get_name (plugin));
+        hashtable_set (new_buffer->local_variables, "name", name);
         
         /* add buffer to buffers list */
         first_buffer_creation = (gui_buffers == NULL);
diff --git a/src/plugins/relay/relay-client-irc.c b/src/plugins/relay/relay-client-irc.c
index 1e7404180..e0ae75210 100644
--- a/src/plugins/relay/relay-client-irc.c
+++ b/src/plugins/relay/relay-client-irc.c
@@ -114,7 +114,7 @@ relay_client_irc_parse_message (const char *message)
                         weechat_prefix ("error"), RELAY_PLUGIN_NAME);
         goto end;
     }
-    weechat_hashtable_set (hash_msg, "message", (char *)message);
+    weechat_hashtable_set (hash_msg, "message", message);
     hash_parsed = weechat_info_get_hashtable ("irc_parse_message",
                                               hash_msg);
     if (!hash_parsed)
diff --git a/src/plugins/scripts/lua/weechat-lua.c b/src/plugins/scripts/lua/weechat-lua.c
index 3486239d4..f22fa9389 100644
--- a/src/plugins/scripts/lua/weechat-lua.c
+++ b/src/plugins/scripts/lua/weechat-lua.c
@@ -131,8 +131,8 @@ weechat_lua_tohashtable (lua_State *interpreter, int index, int hashtable_size)
     while (lua_next (interpreter, index - 1) != 0)
     {
         weechat_hashtable_set (hashtable,
-                               (char *)lua_tostring (interpreter, -2),
-                               (char *)lua_tostring (interpreter, -1));
+                               lua_tostring (interpreter, -2),
+                               lua_tostring (interpreter, -1));
         /* remove value from stack (keep key for next iteration) */
         lua_pop (interpreter, 1);
     }
diff --git a/src/plugins/scripts/python/weechat-python.c b/src/plugins/scripts/python/weechat-python.c
index fb8d46779..dadf38fb7 100644
--- a/src/plugins/scripts/python/weechat-python.c
+++ b/src/plugins/scripts/python/weechat-python.c
@@ -148,7 +148,7 @@ weechat_python_dict_to_hashtable (PyObject *dict, int hashtable_size)
     {
         str_key = PyString_AsString (key);
         str_value = PyString_AsString (value);
-        weechat_hashtable_set (hashtable, (void *)str_key, (void *)str_value);
+        weechat_hashtable_set (hashtable, str_key, str_value);
     }
     
     return hashtable;
diff --git a/src/plugins/scripts/tcl/weechat-tcl.c b/src/plugins/scripts/tcl/weechat-tcl.c
index 9dfd05a0e..27a3190d1 100644
--- a/src/plugins/scripts/tcl/weechat-tcl.c
+++ b/src/plugins/scripts/tcl/weechat-tcl.c
@@ -153,8 +153,8 @@ weechat_tcl_dict_to_hashtable (Tcl_Interp *interp, Tcl_Obj *dict,
         for (; !done ; Tcl_DictObjNext(&search, &key, &value, &done))
         {
             weechat_hashtable_set (hashtable,
-                                   (void *)Tcl_GetString (key),
-                                   (void *)Tcl_GetString (value));
+                                   Tcl_GetString (key),
+                                   Tcl_GetString (value));
         }
     }
     Tcl_DictObjDone(&search);
diff --git a/src/plugins/weechat-plugin.h b/src/plugins/weechat-plugin.h
index 6b340f677..d8a080000 100644
--- a/src/plugins/weechat-plugin.h
+++ b/src/plugins/weechat-plugin.h
@@ -45,7 +45,7 @@ struct timeval;
  */
 
 /* API version (used to check that plugin has same API and can be loaded) */
-#define WEECHAT_PLUGIN_API_VERSION "20101011-01"
+#define WEECHAT_PLUGIN_API_VERSION "20101017-01"
 
 /* macros for defining plugin infos */
 #define WEECHAT_PLUGIN_NAME(__name)                                     \
@@ -260,10 +260,10 @@ struct t_weechat_plugin
                                                                  const void *key1,
                                                                  const void *key2));
     int (*hashtable_set_with_size) (struct t_hashtable *hashtable,
-                                    void *key, int key_size,
-                                    void *value, int value_size);
-    int (*hashtable_set) (struct t_hashtable *hashtable, void *key,
-                          void *value);
+                                    const void *key, int key_size,
+                                    const void *value, int value_size);
+    int (*hashtable_set) (struct t_hashtable *hashtable, const void *key,
+                          const void *value);
     void *(*hashtable_get) (struct t_hashtable *hashtable, const void *key);
     int (*hashtable_has_key) (struct t_hashtable *hashtable, const void *key);
     void (*hashtable_map) (struct t_hashtable *hashtable,