diff --git a/src/xprop.c b/src/xprop.c
index 73ff7ba0..9296c039 100644
--- a/src/xprop.c
+++ b/src/xprop.c
@@ -105,7 +105,7 @@ ex_client_message32_send(EX_Window win, EX_Atom type,
  */
 static void
 _ex_window_prop32_set(EX_Window win, EX_Atom atom,
-		      EX_Atom type, unsigned int *val, int num)
+		      EX_Atom type, const unsigned int *val, int num)
 {
 #if SIZEOF_INT == SIZEOF_LONG
    XChangeProperty(_ex_disp, win, atom, type, 32, PropModeReplace,
@@ -194,7 +194,7 @@ ex_window_prop_del(EX_Window win, EX_Atom atom)
  */
 void
 ex_window_prop_card32_set(EX_Window win, EX_Atom atom,
-			  unsigned int *val, unsigned int num)
+			  const unsigned int *val, unsigned int num)
 {
    _ex_window_prop32_set(win, atom, XA_CARDINAL, val, (int)num);
 }
@@ -389,7 +389,7 @@ _ex_window_prop_string_utf8_get(EX_Window win, EX_Atom atom)
  */
 void
 ex_window_prop_xid_set(EX_Window win, EX_Atom atom, EX_Atom type,
-		       EX_ID * lst, unsigned int num)
+		       const EX_ID * lst, unsigned int num)
 {
    _ex_window_prop32_set(win, atom, type, lst, (int)num);
 }
@@ -481,7 +481,7 @@ ex_window_prop_xid_list_change(EX_Window win, EX_Atom atom,
  */
 void
 ex_window_prop_atom_set(EX_Window win, EX_Atom atom,
-			EX_Atom * lst, unsigned int num)
+			const EX_Atom * lst, unsigned int num)
 {
    ex_window_prop_xid_set(win, atom, XA_ATOM, lst, num);
 }
@@ -530,7 +530,7 @@ ex_window_prop_atom_list_change(EX_Window win, EX_Atom atom,
  */
 void
 ex_window_prop_window_set(EX_Window win, EX_Atom atom,
-			  EX_Window * lst, unsigned int num)
+			  const EX_Window * lst, unsigned int num)
 {
    ex_window_prop_xid_set(win, atom, XA_WINDOW, lst, num);
 }
@@ -846,7 +846,7 @@ ex_netwm_desk_count_set(EX_Window root, unsigned int n_desks)
 }
 
 void
-ex_netwm_desk_roots_set(EX_Window root, EX_Window * vroots,
+ex_netwm_desk_roots_set(EX_Window root, const EX_Window * vroots,
 			unsigned int n_desks)
 {
    ex_window_prop_window_set(root, EX_ATOM_NET_VIRTUAL_ROOTS, vroots, n_desks);
@@ -902,7 +902,7 @@ ex_netwm_desk_size_set(EX_Window root, unsigned int width, unsigned int height)
 }
 
 void
-ex_netwm_desk_workareas_set(EX_Window root, unsigned int *areas,
+ex_netwm_desk_workareas_set(EX_Window root, const unsigned int *areas,
 			    unsigned int n_desks)
 {
    ex_window_prop_card32_set(root, EX_ATOM_NET_WORKAREA, areas, 4 * n_desks);
@@ -915,7 +915,7 @@ ex_netwm_desk_current_set(EX_Window root, unsigned int desk)
 }
 
 void
-ex_netwm_desk_viewports_set(EX_Window root, unsigned int *origins,
+ex_netwm_desk_viewports_set(EX_Window root, const unsigned int *origins,
 			    unsigned int n_desks)
 {
    ex_window_prop_card32_set(root, EX_ATOM_NET_DESKTOP_VIEWPORT,
@@ -937,7 +937,7 @@ ex_netwm_showing_desktop_set(EX_Window root, int on)
 
 /* Mapping order */
 void
-ex_netwm_client_list_set(EX_Window root, EX_Window * p_clients,
+ex_netwm_client_list_set(EX_Window root, const EX_Window * p_clients,
 			 unsigned int n_clients)
 {
    ex_window_prop_window_set(root, EX_ATOM_NET_CLIENT_LIST,
@@ -947,7 +947,8 @@ ex_netwm_client_list_set(EX_Window root, EX_Window * p_clients,
 /* Stacking order */
 void
 ex_netwm_client_list_stacking_set(EX_Window root,
-				  EX_Window * p_clients, unsigned int n_clients)
+				  const EX_Window * p_clients,
+				  unsigned int n_clients)
 {
    ex_window_prop_window_set(root, EX_ATOM_NET_CLIENT_LIST_STACKING,
 			     p_clients, n_clients);
diff --git a/src/xprop.h b/src/xprop.h
index c7c0940a..0f3acc43 100644
--- a/src/xprop.h
+++ b/src/xprop.h
@@ -35,68 +35,53 @@ EX_Atom             ex_atom_get(const char *name);
 void                ex_atoms_get(const char *const *names,
 				 unsigned int num, EX_Atom * atoms);
 
-int                 ex_client_message32_send(EX_Window win,
-					     EX_Atom type,
-					     unsigned int mask,
-					     unsigned int d0,
-					     unsigned int d1,
-					     unsigned int d2,
+int                 ex_client_message32_send(EX_Window win, EX_Atom type,
+					     unsigned int mask, unsigned int d0,
+					     unsigned int d1, unsigned int d2,
 					     unsigned int d3, unsigned int d4);
 
 void                ex_window_prop_del(EX_Window win, EX_Atom atom);
 
-void                ex_window_prop_card32_set(EX_Window win,
-					      EX_Atom atom,
-					      unsigned int *val,
+void                ex_window_prop_card32_set(EX_Window win, EX_Atom atom,
+					      const unsigned int *val,
 					      unsigned int num);
-int                 ex_window_prop_card32_get(EX_Window win,
-					      EX_Atom atom,
+int                 ex_window_prop_card32_get(EX_Window win, EX_Atom atom,
 					      unsigned int *val,
 					      unsigned int len);
-int                 ex_window_prop_card32_list_get(EX_Window win,
-						   EX_Atom atom,
+int                 ex_window_prop_card32_list_get(EX_Window win, EX_Atom atom,
 						   unsigned int **plst);
 
-void                ex_window_prop_xid_set(EX_Window win,
-					   EX_Atom atom,
+void                ex_window_prop_xid_set(EX_Window win, EX_Atom atom,
 					   EX_Atom type,
-					   EX_ID * lst, unsigned int num);
-int                 ex_window_prop_xid_get(EX_Window win,
-					   EX_Atom atom,
+					   const EX_ID * lst, unsigned int num);
+int                 ex_window_prop_xid_get(EX_Window win, EX_Atom atom,
 					   EX_Atom type,
 					   EX_ID * lst, unsigned int len);
-int                 ex_window_prop_xid_list_get(EX_Window win,
-						EX_Atom atom,
+int                 ex_window_prop_xid_list_get(EX_Window win, EX_Atom atom,
 						EX_Atom type, EX_ID ** plst);
-void                ex_window_prop_xid_list_change(EX_Window win,
-						   EX_Atom atom,
+void                ex_window_prop_xid_list_change(EX_Window win, EX_Atom atom,
 						   EX_Atom type,
 						   EX_ID item, int op);
-void                ex_window_prop_atom_set(EX_Window win,
-					    EX_Atom atom,
-					    EX_Atom * val, unsigned int num);
-int                 ex_window_prop_atom_get(EX_Window win,
-					    EX_Atom atom,
+void                ex_window_prop_atom_set(EX_Window win, EX_Atom atom,
+					    const EX_Atom * val,
+					    unsigned int num);
+int                 ex_window_prop_atom_get(EX_Window win, EX_Atom atom,
 					    EX_Atom * val, unsigned int len);
-int                 ex_window_prop_atom_list_get(EX_Window win,
-						 EX_Atom atom, EX_Atom ** plst);
-void                ex_window_prop_atom_list_change(EX_Window win,
-						    EX_Atom atom,
+int                 ex_window_prop_atom_list_get(EX_Window win, EX_Atom atom,
+						 EX_Atom ** plst);
+void                ex_window_prop_atom_list_change(EX_Window win, EX_Atom atom,
 						    EX_Atom item, int op);
-void                ex_window_prop_window_set(EX_Window win,
-					      EX_Atom atom,
-					      EX_Window * val,
+void                ex_window_prop_window_set(EX_Window win, EX_Atom atom,
+					      const EX_Window * val,
 					      unsigned int num);
-int                 ex_window_prop_window_get(EX_Window win,
-					      EX_Atom atom,
+int                 ex_window_prop_window_get(EX_Window win, EX_Atom atom,
 					      EX_Window * val,
 					      unsigned int len);
-int                 ex_window_prop_window_list_get(EX_Window win,
-						   EX_Atom atom,
+int                 ex_window_prop_window_list_get(EX_Window win, EX_Atom atom,
 						   EX_Window ** plst);
 
-void                ex_window_prop_string_set(EX_Window win,
-					      EX_Atom atom, const char *str);
+void                ex_window_prop_string_set(EX_Window win, EX_Atom atom,
+					      const char *str);
 char               *ex_window_prop_string_get(EX_Window win, EX_Atom atom);
 
 /* Misc. */
@@ -252,7 +237,7 @@ void                ex_netwm_wm_identify(EX_Window root,
 void                ex_netwm_desk_count_set(EX_Window root,
 					    unsigned int n_desks);
 void                ex_netwm_desk_roots_set(EX_Window root,
-					    EX_Window * vroots,
+					    const EX_Window * vroots,
 					    unsigned int n_desks);
 void                ex_netwm_desk_names_set(EX_Window root,
 					    const char **names,
@@ -261,22 +246,22 @@ void                ex_netwm_desk_size_set(EX_Window root,
 					   unsigned int width,
 					   unsigned int height);
 void                ex_netwm_desk_workareas_set(EX_Window root,
-						unsigned int *areas,
+						const unsigned int *areas,
 						unsigned int n_desks);
 void                ex_netwm_desk_current_set(EX_Window root,
 					      unsigned int desk);
 void                ex_netwm_desk_viewports_set(EX_Window root,
-						unsigned int *origins,
+						const unsigned int *origins,
 						unsigned int n_desks);
 void                ex_netwm_showing_desktop_set(EX_Window root, int on);
 
 void                ex_netwm_client_list_set(EX_Window root,
-					     EX_Window * p_clients,
+					     const EX_Window * p_clients,
 					     unsigned int n_clients);
 void                ex_netwm_client_list_stacking_set(EX_Window root,
-						      EX_Window *
-						      p_clients, unsigned int
-						      n_clients);
+						      const EX_Window *
+						      p_clients,
+						      unsigned int n_clients);
 void                ex_netwm_client_active_set(EX_Window root, EX_Window win);
 void                ex_netwm_name_set(EX_Window win, const char *name);
 int                 ex_netwm_name_get(EX_Window win, char **name);
@@ -303,10 +288,9 @@ void                ex_icccm_state_set_iconic(EX_Window win);
 void                ex_icccm_state_set_normal(EX_Window win);
 void                ex_icccm_state_set_withdrawn(EX_Window win);
 
-void                ex_window_prop_string_list_set(EX_Window win,
-						   EX_Atom atom,
+void                ex_window_prop_string_list_set(EX_Window win, EX_Atom atom,
 						   char **lst, int num);
-int                 ex_window_prop_string_list_get(EX_Window win,
-						   EX_Atom atom, char ***plst);
+int                 ex_window_prop_string_list_get(EX_Window win, EX_Atom atom,
+						   char ***plst);
 
 #endif /* _XPROP_H_ */