diff --git a/src/config/parse_config.h b/src/config/parse_config.h
index fef246a..9ad0680 100644
--- a/src/config/parse_config.h
+++ b/src/config/parse_config.h
@@ -2858,7 +2858,7 @@ void reapply_monitor_rules(void) {
 }
 
 void reapply_border(void) {
-	Client *c;
+	Client *c = NULL;
 
 	// reset border width when config change
 	wl_list_for_each(c, &clients, link) {
diff --git a/src/dispatch/bind_define.h b/src/dispatch/bind_define.h
index f8269c4..e1ebbaf 100644
--- a/src/dispatch/bind_define.h
+++ b/src/dispatch/bind_define.h
@@ -75,7 +75,7 @@ void exchange_client(const Arg *arg) {
 
 void exchange_stack_client(const Arg *arg) {
 	Client *c = selmon->sel;
-	Client *tc;
+	Client *tc = NULL;
 	if (!c || c->isfloating || c->isfullscreen || c->ismaxmizescreen)
 		return;
 	if (arg->i == NEXT) {
@@ -88,7 +88,7 @@ void exchange_stack_client(const Arg *arg) {
 }
 
 void focusdir(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 	c = direction_select(arg);
 	if (c) {
 		focusclient(c, 1);
@@ -149,7 +149,7 @@ void toggle_trackpad_enable(const Arg *arg) {
 }
 
 void focusmon(const Arg *arg) {
-	Client *c, *old_selmon_sel;
+	Client *c = NULL, *old_selmon_sel = NULL;
 	Monitor *m = NULL;
 
 	if (arg->i != UNDIR) {
@@ -295,7 +295,7 @@ setmfact(const Arg *arg) {
 }
 
 void killclient(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 	c = selmon->sel;
 	if (c) {
 		pending_kill_client(c);
@@ -333,7 +333,7 @@ moveresize(const Arg *arg) {
 }
 
 void movewin(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 	c = selmon->sel;
 	if (!c || c->isfullscreen)
 		return;
@@ -375,7 +375,7 @@ quit(const Arg *arg) {
 }
 
 void resizewin(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 	c = selmon->sel;
 	if (!c || c->isfullscreen)
 		return;
@@ -412,7 +412,7 @@ void resizewin(const Arg *arg) {
 }
 
 void restore_minimized(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 
 	if (selmon && selmon->isoverview)
 		return;
@@ -469,7 +469,7 @@ void set_proportion(const Arg *arg) {
 }
 
 void smartmovewin(const Arg *arg) {
-	Client *c, *tc;
+	Client *c = NULL, *tc = NULL;
 	int nx, ny;
 	int buttom, top, left, right, tar;
 	c = selmon->sel;
@@ -569,7 +569,7 @@ void smartmovewin(const Arg *arg) {
 }
 
 void smartresizewin(const Arg *arg) {
-	Client *c, *tc;
+	Client *c = NULL, *tc = NULL;
 	int nw, nh;
 	int buttom, top, left, right, tar;
 	c = selmon->sel;
@@ -638,7 +638,7 @@ void smartresizewin(const Arg *arg) {
 }
 
 void centerwin(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 	c = selmon->sel;
 
 	if (!c || c->isfullscreen)
@@ -718,7 +718,7 @@ void spawn(const Arg *arg) {
 
 void spawn_on_empty(const Arg *arg) {
 	bool is_empty = true;
-	Client *c;
+	Client *c = NULL;
 
 	wl_list_for_each(c, &clients, link) {
 		if (arg->ui & c->tags && c->mon == selmon) {
@@ -997,8 +997,8 @@ void tagmon(const Arg *arg) {
 }
 
 void tagsilent(const Arg *arg) {
-	Client *fc;
-	Client *target_client;
+	Client *fc = NULL;
+	Client *target_client = NULL;
 
 	if (!selmon || !selmon->sel)
 		return;
@@ -1053,7 +1053,7 @@ void toggle_render_border(const Arg *arg) {
 	arrange(selmon, false);
 }
 void toggle_scratchpad(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 	bool hit = false;
 	Client *tmp = NULL;
 
@@ -1312,7 +1312,7 @@ void comboview(const Arg *arg) {
 }
 
 void zoom(const Arg *arg) {
-	Client *c, *sel = focustop(selmon);
+	Client *c = NULL, *sel = focustop(selmon);
 
 	if (!sel || !selmon ||
 		!selmon->pertag->ltidxs[selmon->pertag->curtag]->arrange ||
diff --git a/src/ext-protocol/dwl-ipc.h b/src/ext-protocol/dwl-ipc.h
index 941f879..e29ac3b 100644
--- a/src/ext-protocol/dwl-ipc.h
+++ b/src/ext-protocol/dwl-ipc.h
@@ -109,7 +109,7 @@ void dwl_ipc_output_printstatus(Monitor *monitor) {
 
 void dwl_ipc_output_printstatus_to(DwlIpcOutput *ipc_output) {
 	Monitor *monitor = ipc_output->mon;
-	Client *c, *focused;
+	Client *c = NULL, *focused = NULL;
 	struct wlr_keyboard *keyboard;
 	xkb_layout_index_t current;
 	int tagmask, state, numclients, focused_client, tag;
@@ -208,7 +208,7 @@ void dwl_ipc_output_set_client_tags(struct wl_client *client,
 									unsigned int xor_tags) {
 	DwlIpcOutput *ipc_output;
 	Monitor *monitor;
-	Client *selected_client;
+	Client *selected_client = NULL;
 	unsigned int newtags = 0;
 
 	ipc_output = wl_resource_get_user_data(resource);
diff --git a/src/fetch/client.h b/src/fetch/client.h
index 79d0bf0..961aac3 100644
--- a/src/fetch/client.h
+++ b/src/fetch/client.h
@@ -18,7 +18,7 @@ bool check_hit_no_border(Client *c) {
 	return hit_no_border;
 }
 Client *termforwin(Client *w) {
-	Client *c;
+	Client *c = NULL;
 
 	if (!w->pid || w->isterm || w->noswallow)
 		return NULL;
@@ -143,7 +143,7 @@ Client *center_tiled_select(Monitor *m) {
 }
 Client *find_client_by_direction(Client *tc, const Arg *arg, bool findfloating,
 								 bool align) {
-	Client *c;
+	Client *c = NULL;
 	Client **tempClients = NULL; // 初始化为 NULL
 	int last = -1;
 
@@ -324,9 +324,8 @@ Client *direction_select(const Arg *arg) {
 /* We probably should change the name of this, it sounds like
  * will focus the topmost client of this mon, when actually will
  * only return that client */
-Client * // 0.5
-focustop(Monitor *m) {
-	Client *c;
+Client *focustop(Monitor *m) {
+	Client *c = NULL;
 	wl_list_for_each(c, &fstack, flink) {
 		if (c->iskilling || c->isunglobal)
 			continue;
diff --git a/src/fetch/monitor.h b/src/fetch/monitor.h
index 2a79b29..630d084 100644
--- a/src/fetch/monitor.h
+++ b/src/fetch/monitor.h
@@ -28,7 +28,7 @@ bool is_scroller_layout(Monitor *m) {
 }
 
 unsigned int get_tag_status(unsigned int tag, Monitor *m) {
-	Client *c;
+	Client *c = NULL;
 	unsigned int status = 0;
 	wl_list_for_each(c, &clients, link) {
 		if (c->mon == m && c->tags & 1 << (tag - 1) & TAGMASK) {
diff --git a/src/layout/horizontal.h b/src/layout/horizontal.h
index e211140..241d58f 100644
--- a/src/layout/horizontal.h
+++ b/src/layout/horizontal.h
@@ -1,6 +1,6 @@
 void fibonacci(Monitor *mon, int s) {
 	unsigned int i = 0, n = 0, nx, ny, nw, nh;
-	Client *c;
+	Client *c = NULL;
 	unsigned int cur_gappih = enablegaps ? mon->gappih : 0;
 	unsigned int cur_gappiv = enablegaps ? mon->gappiv : 0;
 	unsigned int cur_gappoh = enablegaps ? mon->gappoh : 0;
@@ -88,7 +88,7 @@ void fibonacci(Monitor *mon, int s) {
 
 		unsigned int right_gap = 0;
 		unsigned int bottom_gap = 0;
-		Client *nc;
+		Client *nc = NULL;
 
 		wl_list_for_each(nc, &clients, link) {
 			if (!VISIBLEON(nc, mon) || !ISTILED(nc))
@@ -129,7 +129,7 @@ void grid(Monitor *m) {
 	unsigned int cx, cy, cw, ch;
 	unsigned int dx;
 	unsigned int cols, rows, overcols;
-	Client *c;
+	Client *c = NULL;
 	n = 0;
 
 	n = m->isoverview ? m->visible_clients : m->visible_tiling_clients;
@@ -246,7 +246,7 @@ void grid(Monitor *m) {
 void deck(Monitor *m) {
 	unsigned int mw, my;
 	int i, n = 0;
-	Client *c;
+	Client *c = NULL;
 	unsigned int cur_gappih = enablegaps ? m->gappih : 0;
 	unsigned int cur_gappoh = enablegaps ? m->gappoh : 0;
 	unsigned int cur_gappov = enablegaps ? m->gappov : 0;
@@ -304,7 +304,7 @@ void deck(Monitor *m) {
 void scroller(Monitor *m) {
 	unsigned int i, n, j;
 
-	Client *c, *root_client = NULL;
+	Client *c = NULL, *root_client = NULL;
 	Client **tempClients = NULL; // 初始化为 NULL
 	struct wlr_box target_geom;
 	int focus_client_index = 0;
@@ -434,7 +434,7 @@ void scroller(Monitor *m) {
 
 void center_tile(Monitor *m) {
 	unsigned int i, n = 0, h, mw, mx, my, oty, ety, tw;
-	Client *c;
+	Client *c = NULL;
 
 	n = m->visible_tiling_clients;
 	if (n == 0)
@@ -575,7 +575,7 @@ void center_tile(Monitor *m) {
 
 void tile(Monitor *m) {
 	unsigned int i, n = 0, h, r, ie = enablegaps, mw, my, ty;
-	Client *c;
+	Client *c = NULL;
 
 	n = m->visible_tiling_clients;
 
@@ -631,7 +631,7 @@ void tile(Monitor *m) {
 
 void // 17
 monocle(Monitor *m) {
-	Client *c;
+	Client *c = NULL;
 	struct wlr_box geom;
 
 	wl_list_for_each(c, &clients, link) {
diff --git a/src/layout/vertical.h b/src/layout/vertical.h
index c6d7226..ba788c2 100644
--- a/src/layout/vertical.h
+++ b/src/layout/vertical.h
@@ -1,6 +1,6 @@
 void vertical_fibonacci(Monitor *mon, int s) {
 	unsigned int i = 0, n = 0, nx, ny, nw, nh;
-	Client *c;
+	Client *c = NULL;
 	unsigned int cur_gappih = enablegaps ? mon->gappih : 0;
 	unsigned int cur_gappiv = enablegaps ? mon->gappiv : 0;
 	unsigned int cur_gappoh = enablegaps ? mon->gappoh : 0;
@@ -88,7 +88,7 @@ void vertical_fibonacci(Monitor *mon, int s) {
 
 		unsigned int right_gap = 0;
 		unsigned int bottom_gap = 0;
-		Client *nc;
+		Client *nc = NULL;
 
 		wl_list_for_each(nc, &clients, link) {
 			if (!VISIBLEON(nc, mon) || !ISTILED(nc))
@@ -128,7 +128,7 @@ void vertical_grid(Monitor *m) {
 	unsigned int cx, cy, cw, ch;
 	unsigned int dy;
 	unsigned int rows, cols, overrows;
-	Client *c;
+	Client *c = NULL;
 
 	n = m->isoverview ? m->visible_clients : m->visible_tiling_clients;
 
@@ -242,7 +242,7 @@ void vertical_grid(Monitor *m) {
 void vertical_deck(Monitor *m) {
 	unsigned int mh, mx;
 	int i, n = 0;
-	Client *c;
+	Client *c = NULL;
 	unsigned int cur_gappiv = enablegaps ? m->gappiv : 0;
 	unsigned int cur_gappoh = enablegaps ? m->gappoh : 0;
 	unsigned int cur_gappov = enablegaps ? m->gappov : 0;
@@ -294,7 +294,7 @@ void vertical_deck(Monitor *m) {
 
 void vertical_scroller(Monitor *m) {
 	unsigned int i, n, j;
-	Client *c, *root_client = NULL;
+	Client *c = NULL, *root_client = NULL;
 	Client **tempClients = NULL;
 	struct wlr_box target_geom;
 	int focus_client_index = 0;
@@ -421,7 +421,7 @@ void vertical_scroller(Monitor *m) {
 
 void vertical_tile(Monitor *m) {
 	unsigned int i, n = 0, w, r, ie = enablegaps, mh, mx, tx;
-	Client *c;
+	Client *c = NULL;
 
 	n = m->visible_tiling_clients;
 
diff --git a/src/mango.c b/src/mango.c
index 3162f8e..3e92546 100644
--- a/src/mango.c
+++ b/src/mango.c
@@ -1227,7 +1227,7 @@ void applyrules(Client *c) {
 	unsigned int i, newtags = 0;
 	const ConfigWinRule *r;
 	Monitor *mon = selmon, *m;
-	Client *fc;
+	Client *fc = NULL;
 	bool hit_rule_pos = false;
 
 	c->isfloating = client_is_float_type(c);
@@ -1360,7 +1360,7 @@ void applyrules(Client *c) {
 
 void // 17
 arrange(Monitor *m, bool want_animation) {
-	Client *c;
+	Client *c = NULL;
 
 	if (!m)
 		return;
@@ -1446,7 +1446,7 @@ void apply_window_snap(Client *c) {
 	cw = c->geom.width - 2 * cbw;
 	ch = c->geom.height - 2 * cbw;
 
-	Client *tc;
+	Client *tc = NULL;
 	if (!c || !c->mon || !client_surface(c)->mapped || c->iskilling)
 		return;
 
@@ -1817,10 +1817,10 @@ buttonpress(struct wl_listener *listener, void *data) {
 	struct wlr_pointer_button_event *event = data;
 	struct wlr_keyboard *hard_keyboard, *keyboard;
 	unsigned int hard_mods, mods;
-	Client *c;
-	LayerSurface *l;
+	Client *c = NULL;
+	LayerSurface *l = NULL;
 	struct wlr_surface *surface;
-	Client *tmpc;
+	Client *tmpc = NULL;
 	int ji;
 	const MouseBinding *m;
 	struct wlr_surface *old_pointer_focus_surface =
@@ -2075,7 +2075,7 @@ void cleanupmon(struct wl_listener *listener, void *data) {
 void closemon(Monitor *m) {
 	/* update selmon if needed and
 	 * move closed monitor's clients to the focused one */
-	Client *c;
+	Client *c = NULL;
 	int i = 0, nmons = wl_list_length(&mons);
 	if (!nmons) {
 		selmon = NULL;
@@ -3537,7 +3537,7 @@ void // old fix to 0.5
 mapnotify(struct wl_listener *listener, void *data) {
 	/* Called when the surface is mapped, or ready to display on-screen. */
 	Client *p = NULL;
-	Client *at_client;
+	Client *at_client = NULL;
 	Client *c = wl_container_of(listener, c, map);
 	/* Create scene tree for this client and its border */
 	c->scene = client_surface(c)->data = wlr_scene_tree_create(layers[LyrTile]);
@@ -4071,7 +4071,7 @@ void client_set_opacity(Client *c, double opacity) {
 
 void rendermon(struct wl_listener *listener, void *data) {
 	Monitor *m = wl_container_of(listener, m, frame);
-	Client *c, *tmp;
+	Client *c = NULL, *tmp = NULL;
 	struct wlr_output_state pending = {0};
 	LayerSurface *l, *tmpl;
 	int i;
@@ -4321,7 +4321,7 @@ void setcursor(struct wl_listener *listener, void *data) {
 void // 0.5
 setfloating(Client *c, int floating) {
 
-	Client *fc;
+	Client *fc = NULL;
 	int hit;
 	struct wlr_box target_box, backup_box;
 	c->isfloating = floating;
@@ -4988,7 +4988,7 @@ void startdrag(struct wl_listener *listener, void *data) {
 }
 
 void tag_client(const Arg *arg, Client *target_client) {
-	Client *fc;
+	Client *fc = NULL;
 	if (target_client && arg->ui & TAGMASK) {
 
 		target_client->tags = arg->ui & TAGMASK;
@@ -5109,7 +5109,7 @@ int hidecursor(void *data) {
 
 // 显示所有tag 或 跳转到聚焦窗口的tag
 void toggleoverview(const Arg *arg) {
-	Client *c;
+	Client *c = NULL;
 
 	if (selmon->isoverview && ov_tab_mode && arg->i != -1 && selmon->sel) {
 		focusstack(&(Arg){.i = 1});
@@ -5287,7 +5287,7 @@ void updatemons(struct wl_listener *listener, void *data) {
 	 */
 	struct wlr_output_configuration_v1 *config =
 		wlr_output_configuration_v1_create();
-	Client *c;
+	Client *c = NULL;
 	struct wlr_output_configuration_head_v1 *config_head;
 	Monitor *m;
 	int mon_pos_offsetx, mon_pos_offsety, oldx, oldy;
@@ -5633,7 +5633,7 @@ void configurex11(struct wl_listener *listener, void *data) {
 
 void createnotifyx11(struct wl_listener *listener, void *data) {
 	struct wlr_xwayland_surface *xsurface = data;
-	Client *c;
+	Client *c = NULL;
 
 	/* Allocate a Client for this surface */
 	c = xsurface->data = ecalloc(1, sizeof(*c));