diff --git a/include/floating.h b/include/floating.h
index 417e47ea..e97029f5 100644
--- a/include/floating.h
+++ b/include/floating.h
@@ -13,12 +13,12 @@
 #include "tree.h"
 
 /** Callback for dragging */
-typedef void(*callback_t)(Con*, Rect*, uint32_t, uint32_t, void*);
+typedef void(*callback_t)(Con*, Rect*, uint32_t, uint32_t, const void*);
 
 /** Macro to create a callback function for dragging */
 #define DRAGGING_CB(name) \
         static void name(Con *con, Rect *old_rect, uint32_t new_x, \
-                         uint32_t new_y, void *extra)
+                         uint32_t new_y, const void *extra)
 
 /** On which border was the dragging initiated? */
 typedef enum { BORDER_LEFT   = (1 << 0),
@@ -89,7 +89,7 @@ int floating_border_click(xcb_connection_t *conn, Client *client,
  * Calls the drag_pointer function with the drag_window callback
  *
  */
-void floating_drag_window(Con *con, xcb_button_press_event_t *event);
+void floating_drag_window(Con *con, const xcb_button_press_event_t *event);
 
 /**
  * Called when the user clicked on a floating window while holding the
@@ -97,7 +97,7 @@ void floating_drag_window(Con *con, xcb_button_press_event_t *event);
  * Calls the drag_pointer function with the resize_window callback
  *
  */
-void floating_resize_window(Con *con, bool proportional, xcb_button_press_event_t *event);
+void floating_resize_window(Con *con, const bool proportional, const xcb_button_press_event_t *event);
 
 #if 0
 /**
@@ -133,8 +133,8 @@ void floating_toggle_hide(xcb_connection_t *conn, Workspace *workspace);
  * the event and the new coordinates (x, y).
  *
  */
-void drag_pointer(Con *con, xcb_button_press_event_t *event,
+void drag_pointer(Con *con, const xcb_button_press_event_t *event,
                   xcb_window_t confine_to, border_t border, callback_t callback,
-                  void *extra);
+                  const void *extra);
 
 #endif
diff --git a/include/resize.h b/include/resize.h
index d530294b..99646ea0 100644
--- a/include/resize.h
+++ b/include/resize.h
@@ -10,6 +10,6 @@
 #ifndef _RESIZE_H
 #define _RESIZE_H
 
-int resize_graphical_handler(Con *first, Con *second, orientation_t orientation, xcb_button_press_event_t *event);
+int resize_graphical_handler(Con *first, Con *second, orientation_t orientation, const xcb_button_press_event_t *event);
 
 #endif
diff --git a/src/click.c b/src/click.c
index 8121e160..d0adc231 100644
--- a/src/click.c
+++ b/src/click.c
@@ -25,7 +25,7 @@ typedef enum { CLICK_BORDER = 0, CLICK_DECORATION = 1, CLICK_INSIDE = 2 } click_
  * then calls resize_graphical_handler().
  *
  */
-static bool tiling_resize_for_border(Con *con, border_t border, xcb_button_press_event_t *event) {
+static bool tiling_resize_for_border(Con *con, border_t border, const xcb_button_press_event_t *event) {
     DLOG("border = %d\n", border);
     char way = (border == BORDER_TOP || border == BORDER_LEFT ? 'p' : 'n');
     orientation_t orientation = (border == BORDER_TOP || border == BORDER_BOTTOM ? VERT : HORIZ);
@@ -76,7 +76,7 @@ static bool tiling_resize_for_border(Con *con, border_t border, xcb_button_press
  * to the client).
  *
  */
-static bool floating_mod_on_tiled_client(Con *con, xcb_button_press_event_t *event) {
+static bool floating_mod_on_tiled_client(Con *con, const xcb_button_press_event_t *event) {
     /* The client is in tiling layout. We can still initiate a resize with the
      * right mouse button, by chosing the border which is the most near one to
      * the position of the mouse pointer */
@@ -115,7 +115,7 @@ static bool floating_mod_on_tiled_client(Con *con, xcb_button_press_event_t *eve
  * Finds out which border was clicked on and calls tiling_resize_for_border().
  *
  */
-static bool tiling_resize(Con *con, xcb_button_press_event_t *event, click_destination_t dest) {
+static bool tiling_resize(Con *con, const xcb_button_press_event_t *event, const click_destination_t dest) {
     /* check if this was a click on the window border (and on which one) */
     Rect bsr = con_border_style_rect(con);
     DLOG("BORDER x = %d, y = %d for con %p, window 0x%08x\n",
@@ -165,7 +165,7 @@ static bool tiling_resize(Con *con, xcb_button_press_event_t *event, click_desti
  * functions for resizing/dragging.
  *
  */
-static int route_click(Con *con, xcb_button_press_event_t *event, bool mod_pressed, click_destination_t dest) {
+static int route_click(Con *con, const xcb_button_press_event_t *event, const bool mod_pressed, const click_destination_t dest) {
     DLOG("--> click properties: mod = %d, destination = %d\n", mod_pressed, dest);
     DLOG("--> OUTCOME = %p\n", con);
     DLOG("type = %d, name = %s\n", con->type, con->name);
@@ -279,7 +279,7 @@ int handle_button_press(xcb_button_press_event_t *event) {
     last_timestamp = event->time;
 
     const uint32_t mod = config.floating_modifier;
-    bool mod_pressed = (mod != 0 && (event->state & mod) == mod);
+    const bool mod_pressed = (mod != 0 && (event->state & mod) == mod);
     DLOG("floating_mod = %d, detail = %d\n", mod_pressed, event->detail);
     if ((con = con_by_window_id(event->event)))
         return route_click(con, event, mod_pressed, CLICK_INSIDE);
diff --git a/src/floating.c b/src/floating.c
index 83e20ee2..90e5024e 100644
--- a/src/floating.c
+++ b/src/floating.c
@@ -296,7 +296,7 @@ bool floating_maybe_reassign_ws(Con *con) {
 }
 
 DRAGGING_CB(drag_window_callback) {
-    struct xcb_button_press_event_t *event = extra;
+    const struct xcb_button_press_event_t *event = extra;
 
     /* Reposition the client correctly while moving */
     con->rect.x = old_rect->x + (new_x - event->root_x);
@@ -317,7 +317,7 @@ DRAGGING_CB(drag_window_callback) {
  * Calls the drag_pointer function with the drag_window callback
  *
  */
-void floating_drag_window(Con *con, xcb_button_press_event_t *event) {
+void floating_drag_window(Con *con, const xcb_button_press_event_t *event) {
     DLOG("floating_drag_window\n");
 
     /* Push changes before dragging, so that the window gets raised now and not
@@ -337,14 +337,14 @@ void floating_drag_window(Con *con, xcb_button_press_event_t *event) {
  *
  */
 struct resize_window_callback_params {
-    border_t corner;
-    bool proportional;
-    xcb_button_press_event_t *event;
+    const border_t corner;
+    const bool proportional;
+    const xcb_button_press_event_t *event;
 };
 
 DRAGGING_CB(resize_window_callback) {
-    struct resize_window_callback_params *params = extra;
-    xcb_button_press_event_t *event = params->event;
+    const struct resize_window_callback_params *params = extra;
+    const xcb_button_press_event_t *event = params->event;
     border_t corner = params->corner;
 
     int32_t dest_x = con->rect.x;
@@ -397,8 +397,8 @@ DRAGGING_CB(resize_window_callback) {
  * Calls the drag_pointer function with the resize_window callback
  *
  */
-void floating_resize_window(Con *con, bool proportional,
-                            xcb_button_press_event_t *event) {
+void floating_resize_window(Con *con, const bool proportional,
+                            const xcb_button_press_event_t *event) {
     DLOG("floating_resize_window\n");
 
     /* corner saves the nearest corner to the original click. It contains
@@ -426,8 +426,8 @@ void floating_resize_window(Con *con, bool proportional,
  * the event and the new coordinates (x, y).
  *
  */
-void drag_pointer(Con *con, xcb_button_press_event_t *event, xcb_window_t
-                confine_to, border_t border, callback_t callback, void *extra)
+void drag_pointer(Con *con, const xcb_button_press_event_t *event, xcb_window_t
+                confine_to, border_t border, callback_t callback, const void *extra)
 {
     uint32_t new_x, new_y;
     Rect old_rect;
diff --git a/src/resize.c b/src/resize.c
index 8f8c04d7..a4e4dfa0 100644
--- a/src/resize.c
+++ b/src/resize.c
@@ -26,7 +26,7 @@ struct callback_params {
 };
 
 DRAGGING_CB(resize_callback) {
-    struct callback_params *params = extra;
+    const struct callback_params *params = extra;
     Con *output = params->output;
     DLOG("new x = %d, y = %d\n", new_x, new_y);
     if (params->orientation == HORIZ) {
@@ -49,7 +49,7 @@ DRAGGING_CB(resize_callback) {
     xcb_flush(conn);
 }
 
-int resize_graphical_handler(Con *first, Con *second, orientation_t orientation, xcb_button_press_event_t *event) {
+int resize_graphical_handler(Con *first, Con *second, orientation_t orientation, const xcb_button_press_event_t *event) {
     DLOG("resize handler\n");
 
     uint32_t new_position;
@@ -98,7 +98,7 @@ int resize_graphical_handler(Con *first, Con *second, orientation_t orientation,
 
     xcb_flush(conn);
 
-    struct callback_params params = { orientation, output, helpwin, &new_position };
+    const struct callback_params params = { orientation, output, helpwin, &new_position };
 
     drag_pointer(NULL, event, grabwin, BORDER_TOP, resize_callback, &params);