diff --git a/glfw/glfw.py b/glfw/glfw.py
index 8605ec65d..b957bb3c0 100755
--- a/glfw/glfw.py
+++ b/glfw/glfw.py
@@ -285,7 +285,7 @@ def generate_wrappers(glfw_header: str) -> None:
     int glfwCocoaSetBackgroundBlur(GLFWwindow *w, int blur_radius)
     bool glfwSetX11WindowBlurred(GLFWwindow *w, bool enable_blur)
     void* glfwGetX11Display(void)
-    int32_t glfwGetX11Window(GLFWwindow* window)
+    unsigned long glfwGetX11Window(GLFWwindow* window)
     void glfwSetPrimarySelectionString(GLFWwindow* window, const char* string)
     void glfwCocoaSetWindowChrome(GLFWwindow* window, unsigned int color, bool use_system_color, unsigned int system_color,\
     int background_blur, unsigned int hide_window_decorations, bool show_text_in_titlebar, int color_space, float background_opacity, bool resizable)
diff --git a/glfw/x11_window.c b/glfw/x11_window.c
index 3b940d2ee..cd958e1bf 100644
--- a/glfw/x11_window.c
+++ b/glfw/x11_window.c
@@ -41,7 +41,6 @@
 #include <stdlib.h>
 #include <limits.h>
 #include <errno.h>
-#include <assert.h>
 
 // Action for EWMH client messages
 #define _NET_WM_STATE_REMOVE        0
@@ -3227,7 +3226,7 @@ GLFWAPI Display* glfwGetX11Display(void)
     return _glfw.x11.display;
 }
 
-GLFWAPI Window glfwGetX11Window(GLFWwindow* handle)
+GLFWAPI unsigned long glfwGetX11Window(GLFWwindow* handle)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(None);
diff --git a/kitty/fonts.c b/kitty/fonts.c
index ed0733849..ae746b563 100644
--- a/kitty/fonts.c
+++ b/kitty/fonts.c
@@ -15,9 +15,8 @@
 #define MISSING_GLYPH (NUM_UNDERLINE_STYLES + 2)
 #define MAX_NUM_EXTRA_GLYPHS_PUA 4u
 
-typedef void (*send_sprite_to_gpu_func)(FONTS_DATA_HANDLE fg, unsigned int, unsigned int, unsigned int, pixel*);
-send_sprite_to_gpu_func current_send_sprite_to_gpu = NULL;
 static PyObject *python_send_to_gpu_impl = NULL;
+#define current_send_sprite_to_gpu(...) (python_send_to_gpu_impl ? python_send_to_gpu(__VA_ARGS__) : send_sprite_to_gpu(__VA_ARGS__))
 extern PyTypeObject Line_Type;
 
 enum {NO_FONT=-3, MISSING_FONT=-2, BLANK_FONT=-1, BOX_FONT=0};
@@ -1580,7 +1579,6 @@ set_send_sprite_to_gpu(PyObject UNUSED *self, PyObject *func) {
         python_send_to_gpu_impl = func;
         Py_INCREF(python_send_to_gpu_impl);
     }
-    current_send_sprite_to_gpu = python_send_to_gpu_impl ? python_send_to_gpu : send_sprite_to_gpu;
     Py_RETURN_NONE;
 }
 
@@ -1738,6 +1736,5 @@ init_fonts(PyObject *module) {
     create_feature("-calt", CALT_FEATURE);
 #undef create_feature
     if (PyModule_AddFunctions(module, module_methods) != 0) return false;
-    current_send_sprite_to_gpu = send_sprite_to_gpu;
     return true;
 }
diff --git a/kitty/glfw-wrapper.h b/kitty/glfw-wrapper.h
index d2c506780..3e43bf81c 100644
--- a/kitty/glfw-wrapper.h
+++ b/kitty/glfw-wrapper.h
@@ -2258,7 +2258,7 @@ typedef void* (*glfwGetX11Display_func)(void);
 GFW_EXTERN glfwGetX11Display_func glfwGetX11Display_impl;
 #define glfwGetX11Display glfwGetX11Display_impl
 
-typedef int32_t (*glfwGetX11Window_func)(GLFWwindow*);
+typedef unsigned long (*glfwGetX11Window_func)(GLFWwindow*);
 GFW_EXTERN glfwGetX11Window_func glfwGetX11Window_impl;
 #define glfwGetX11Window glfwGetX11Window_impl
 
diff --git a/kitty/glfw.c b/kitty/glfw.c
index 9076b6891..32dd05128 100644
--- a/kitty/glfw.c
+++ b/kitty/glfw.c
@@ -1044,7 +1044,7 @@ native_window_handle(GLFWwindow *w) {
     void *ans = glfwGetCocoaWindow(w);
     return PyLong_FromVoidPtr(ans);
 #endif
-    if (glfwGetX11Window) return PyLong_FromLong((long)glfwGetX11Window(w));
+    if (glfwGetX11Window) return PyLong_FromUnsignedLong(glfwGetX11Window(w));
     return Py_None;
 }
 
@@ -1768,7 +1768,7 @@ x11_window_id(PyObject UNUSED *self, PyObject *os_wid) {
     OSWindow *w = os_window_for_id(PyLong_AsUnsignedLongLong(os_wid));
     if (!w) { PyErr_SetString(PyExc_ValueError, "No OSWindow with the specified id found"); return NULL; }
     if (!glfwGetX11Window) { PyErr_SetString(PyExc_RuntimeError, "Failed to load glfwGetX11Window"); return NULL; }
-    return Py_BuildValue("l", (long)glfwGetX11Window(w->handle));
+    return PyLong_FromUnsignedLong(glfwGetX11Window(w->handle));
 }
 
 static PyObject*