diff --git a/arch/sim/src/sim/posix/sim_x11framebuffer.c b/arch/sim/src/sim/posix/sim_x11framebuffer.c
index a5b90978b5..701f14246f 100644
--- a/arch/sim/src/sim/posix/sim_x11framebuffer.c
+++ b/arch/sim/src/sim/posix/sim_x11framebuffer.c
@@ -106,6 +106,8 @@ static inline Display *sim_x11createframe(void)
 
   XSetWMProperties(display, g_window, &winprop, &iconprop, argv, 1,
                    &hints, NULL, NULL);
+  XFree(winprop.value);
+  XFree(iconprop.value);
 
   /* Select window input events */