Index: src/client.c
===================================================================
--- src/client.c	(revision 22054)
+++ src/client.c	(working copy)
@@ -3376,6 +3376,7 @@
                 passdata->move_resized = TRUE;
                 passdata->ox = c->x;
                 passdata->mx = c->x + c->width * xratio;
+                passdata->mx = CLAMP(passdata->mx, c->x, c->x + c->width);
                 passdata->oy = c->y;
                 passdata->my = c->y - frameTop(c) / 2;
                 toggled_maximize = TRUE;