diff --git a/src/core/wee-hdata.c b/src/core/wee-hdata.c
index f6fa214a1..be5bc4d6a 100644
--- a/src/core/wee-hdata.c
+++ b/src/core/wee-hdata.c
@@ -1062,6 +1062,9 @@ hdata_get_string (struct t_hdata *hdata, const char *property)
 void
 hdata_free (struct t_hdata *hdata)
 {
+    if (!hdata)
+        return;
+
     if (hdata->hash_var)
         hashtable_free (hdata->hash_var);
     if (hdata->var_prev)
diff --git a/src/core/wee-infolist.c b/src/core/wee-infolist.c
index 070cd685c..99678cfbb 100644
--- a/src/core/wee-infolist.c
+++ b/src/core/wee-infolist.c
@@ -584,6 +584,9 @@ infolist_var_free (struct t_infolist_item *item,
 {
     struct t_infolist_var *new_vars;
 
+    if (!item || !var)
+        return;
+
     /* remove var */
     if (item->last_var == var)
         item->last_var = var->prev_var;
@@ -625,6 +628,9 @@ infolist_item_free (struct t_infolist *infolist,
 {
     struct t_infolist_item *new_items;
 
+    if (!infolist || !item)
+        return;
+
     /* remove var */
     if (infolist->last_item == item)
         infolist->last_item = item->prev_item;
@@ -661,6 +667,9 @@ infolist_free (struct t_infolist *infolist)
 {
     struct t_infolist *new_weechat_infolists;
 
+    if (!infolist)
+        return;
+
     /* remove list */
     if (last_weechat_infolist == infolist)
         last_weechat_infolist = infolist->prev_infolist;
diff --git a/src/core/wee-string.c b/src/core/wee-string.c
index b652abf14..3003bcf8b 100644
--- a/src/core/wee-string.c
+++ b/src/core/wee-string.c
@@ -3184,6 +3184,9 @@ string_shared_free (const char *string)
 {
     string_shared_count_t *ptr_count;
 
+    if (!string)
+        return;
+
     ptr_count = (string_shared_count_t *)(string - sizeof (string_shared_count_t));
 
     (*ptr_count)--;
diff --git a/src/gui/curses/gui-curses-window.c b/src/gui/curses/gui-curses-window.c
index 05bd4e407..bda0b7e10 100644
--- a/src/gui/curses/gui-curses-window.c
+++ b/src/gui/curses/gui-curses-window.c
@@ -146,6 +146,9 @@ gui_window_objects_init (struct t_gui_window *window)
 void
 gui_window_objects_free (struct t_gui_window *window, int free_separators)
 {
+    if (!window)
+        return;
+
     if (GUI_WINDOW_OBJECTS(window)->win_chat)
     {
         delwin (GUI_WINDOW_OBJECTS(window)->win_chat);
diff --git a/src/gui/gui-color.c b/src/gui/gui-color.c
index 747fb840e..fcfb2a9bd 100644
--- a/src/gui/gui-color.c
+++ b/src/gui/gui-color.c
@@ -1147,13 +1147,13 @@ gui_color_emphasize (const char *string,
 void
 gui_color_free (struct t_gui_color *color)
 {
-    if (color)
-    {
-        if (color->string)
-            free (color->string);
+    if (!color)
+        return;
 
-        free (color);
-    }
+    if (color->string)
+        free (color->string);
+
+    free (color);
 }
 
 /*
diff --git a/src/gui/gui-completion.c b/src/gui/gui-completion.c
index 9b6a12242..d5ece75fe 100644
--- a/src/gui/gui-completion.c
+++ b/src/gui/gui-completion.c
@@ -200,7 +200,11 @@ gui_completion_free_data (struct t_gui_completion *completion)
 void
 gui_completion_free (struct t_gui_completion *completion)
 {
+    if (!completion)
+        return;
+
     gui_completion_free_data (completion);
+
     free (completion);
 }
 
diff --git a/src/gui/gui-filter.c b/src/gui/gui-filter.c
index 3b50f1922..e32f2be4a 100644
--- a/src/gui/gui-filter.c
+++ b/src/gui/gui-filter.c
@@ -467,6 +467,9 @@ gui_filter_free (struct t_gui_filter *filter)
 {
     int i;
 
+    if (!filter)
+        return;
+
     (void) hook_signal_send ("filter_removing",
                              WEECHAT_HOOK_SIGNAL_POINTER, filter);
 
diff --git a/src/gui/gui-history.c b/src/gui/gui-history.c
index 8fbf4583a..2eaaf68d8 100644
--- a/src/gui/gui-history.c
+++ b/src/gui/gui-history.c
@@ -201,6 +201,9 @@ gui_history_buffer_free (struct t_gui_buffer *buffer)
 {
     struct t_gui_history *ptr_history;
 
+    if (!buffer)
+        return;
+
     while (buffer->history)
     {
         ptr_history = buffer->history->next_history;
diff --git a/src/gui/gui-hotlist.c b/src/gui/gui-hotlist.c
index c7cc1700d..9bbcf65e0 100644
--- a/src/gui/gui-hotlist.c
+++ b/src/gui/gui-hotlist.c
@@ -96,6 +96,9 @@ gui_hotlist_free (struct t_gui_hotlist **hotlist,
 {
     struct t_gui_hotlist *new_hotlist;
 
+    if (!ptr_hotlist)
+        return;
+
     /* remove hotlist from queue */
     if (*last_hotlist == ptr_hotlist)
         *last_hotlist = ptr_hotlist->prev_hotlist;
diff --git a/src/gui/gui-key.c b/src/gui/gui-key.c
index 8da3bb666..e7255fb96 100644
--- a/src/gui/gui-key.c
+++ b/src/gui/gui-key.c
@@ -1435,6 +1435,9 @@ gui_key_free (struct t_gui_key **keys, struct t_gui_key **last_key,
 {
     int i;
 
+    if (!key)
+        return;
+
     /* free memory */
     if (key->key)
         free (key->key);
diff --git a/src/gui/gui-line.c b/src/gui/gui-line.c
index 70296d0c7..63cfa6523 100644
--- a/src/gui/gui-line.c
+++ b/src/gui/gui-line.c
@@ -83,6 +83,9 @@ gui_lines_alloc ()
 void
 gui_lines_free (struct t_gui_lines *lines)
 {
+    if (!lines)
+        return;
+
     free (lines);
 }
 
@@ -112,6 +115,9 @@ gui_line_tags_alloc (struct t_gui_line_data *line_data, const char *tags)
 void
 gui_line_tags_free (struct t_gui_line_data *line_data)
 {
+    if (!line_data)
+        return;
+
     if (line_data->tags_array)
     {
         string_free_split_shared (line_data->tags_array);
@@ -1120,6 +1126,9 @@ gui_line_free (struct t_gui_buffer *buffer, struct t_gui_line *line)
 {
     struct t_gui_line *ptr_line;
 
+    if (!buffer || !line)
+        return;
+
     /* first remove mixed line if it exists */
     if (buffer->mixed_lines)
     {
diff --git a/src/gui/gui-window.c b/src/gui/gui-window.c
index 5713125b1..f3aaafc31 100644
--- a/src/gui/gui-window.c
+++ b/src/gui/gui-window.c
@@ -332,15 +332,16 @@ gui_window_tree_node_to_leaf (struct t_gui_window_tree *node,
 void
 gui_window_tree_free (struct t_gui_window_tree **tree)
 {
-    if (*tree)
-    {
-        if ((*tree)->child1)
-            gui_window_tree_free (&((*tree)->child1));
-        if ((*tree)->child2)
-            gui_window_tree_free (&((*tree)->child2));
-        free (*tree);
-        *tree = NULL;
-    }
+    if (!tree || !*tree)
+        return;
+
+    if ((*tree)->child1)
+        gui_window_tree_free (&((*tree)->child1));
+    if ((*tree)->child2)
+        gui_window_tree_free (&((*tree)->child2));
+
+    free (*tree);
+    *tree = NULL;
 }
 
 /*
@@ -418,6 +419,9 @@ void
 gui_window_scroll_free (struct t_gui_window *window,
                         struct t_gui_window_scroll *scroll)
 {
+    if (!window || !scroll)
+        return;
+
     if (scroll->prev_scroll)
         (scroll->prev_scroll)->next_scroll = scroll->next_scroll;
     if (scroll->next_scroll)