diff --git a/config.def.h b/config.def.h
index 1c0b587..ae7af3b 100644
--- a/config.def.h
+++ b/config.def.h
@@ -26,9 +26,9 @@ static const Rule rules[] = {
 	 *	WM_CLASS(STRING) = instance, class
 	 *	WM_NAME(STRING) = title
 	 */
-	/* class      instance    title       tags mask     isfloating   monitor */
-	{ "Gimp",     NULL,       NULL,       0,            1,           -1 },
-	{ "Firefox",  NULL,       NULL,       1 << 8,       0,           -1 },
+	/* class      instance    title       tags mask     iscentered     isfloating   monitor */
+	{ "Gimp",     NULL,       NULL,       0,            0,             1,           -1 },
+	{ "Firefox",  NULL,       NULL,       1 << 8,       0,             0,           -1 },
 };
 
 /* layout(s) */
diff --git a/dwm.c b/dwm.c
index 4465af1..33b753f 100644
--- a/dwm.c
+++ b/dwm.c
@@ -92,7 +92,7 @@ struct Client {
 	int basew, baseh, incw, inch, maxw, maxh, minw, minh;
 	int bw, oldbw;
 	unsigned int tags;
-	int isfixed, isfloating, isurgent, neverfocus, oldstate, isfullscreen;
+	int isfixed, iscentered, isfloating, isurgent, neverfocus, oldstate, isfullscreen;
 	Client *next;
 	Client *snext;
 	Monitor *mon;
@@ -137,6 +137,7 @@ typedef struct {
 	const char *instance;
 	const char *title;
 	unsigned int tags;
+	int iscentered;
 	int isfloating;
 	int monitor;
 } Rule;
@@ -297,6 +298,7 @@ applyrules(Client *c)
 		&& (!r->class || strstr(class, r->class))
 		&& (!r->instance || strstr(instance, r->instance)))
 		{
+			c->iscentered = r->iscentered;
 			c->isfloating = r->isfloating;
 			c->tags |= r->tags;
 			for (m = mons; m && m->num != r->monitor; m = m->next);
@@ -1017,6 +1019,7 @@ killclient(const Arg *arg)
 void
 manage(Window w, XWindowAttributes *wa)
 {
+    Monitor *m;
 	Client *c, *t = NULL;
 	Window trans = None;
 	XWindowChanges wc;
@@ -1060,8 +1063,15 @@ manage(Window w, XWindowAttributes *wa)
 	grabbuttons(c, 0);
 	if (!c->isfloating)
 		c->isfloating = c->oldstate = trans != None || c->isfixed;
-	if (c->isfloating)
+	if (c->isfloating){
 		XRaiseWindow(dpy, c->win);
+        if(c->iscentered) {
+            c->x = (c->mon->mw - WIDTH(c)) / 2;
+            c->y = (c->mon->mh - HEIGHT(c)) / 2;
+            for (m=mons; m != c->mon; m = m->next)
+                c->x += m->mw;
+        }
+    }
 	attach(c);
 	attachstack(c);
 	XChangeProperty(dpy, root, netatom[NetClientList], XA_WINDOW, 32, PropModeAppend,