diff --git a/src/x11_init.c b/src/x11_init.c
index fd1ccb91..f16f9604 100644
--- a/src/x11_init.c
+++ b/src/x11_init.c
@@ -864,6 +864,8 @@ static GLFWbool initExtensions(void)
             _glfw_dlsym(_glfw.x11.xshape.handle, "XShapeCombineRegion");
         _glfw.x11.xshape.QueryVersion = (PFN_XShapeQueryVersion)
             _glfw_dlsym(_glfw.x11.xshape.handle, "XShapeQueryVersion");
+        _glfw.x11.xshape.ShapeCombineMask = (PFN_XShapeCombineMask)
+            _glfw_dlsym(_glfw.x11.xshape.handle, "XShapeCombineMask");
 
         if (XShapeQueryExtension(_glfw.x11.display,
             &_glfw.x11.xshape.errorBase,
@@ -1285,8 +1287,6 @@ int _glfwPlatformInit(void)
         _glfw_dlsym(_glfw.x11.xlib.handle, "XUndefineCursor");
     _glfw.x11.xlib.UngrabPointer = (PFN_XUngrabPointer)
         _glfw_dlsym(_glfw.x11.xlib.handle, "XUngrabPointer");
-    _glfw.x11.xlib.UnionRectWithRegion = (PFN_XUnionRectWithRegion)
-        _glfw_dlsym(_glfw.x11.xlib.handle, "XUnionRectWithRegion");
     _glfw.x11.xlib.UnmapWindow = (PFN_XUnmapWindow)
         _glfw_dlsym(_glfw.x11.xlib.handle, "XUnmapWindow");
     _glfw.x11.xlib.UnsetICFocus = (PFN_XUnsetICFocus)
diff --git a/src/x11_platform.h b/src/x11_platform.h
index ab2f3aec..c879df4c 100644
--- a/src/x11_platform.h
+++ b/src/x11_platform.h
@@ -129,7 +129,6 @@ typedef int (* PFN_XSync)(Display*,Bool);
 typedef Bool (* PFN_XTranslateCoordinates)(Display*,Window,Window,int,int,int*,int*,Window*);
 typedef int (* PFN_XUndefineCursor)(Display*,Window);
 typedef int (* PFN_XUngrabPointer)(Display*,Time);
-typedef int (* PFN_XUnionRectWithRegion)(XRectangle*,Region,Region);
 typedef int (* PFN_XUnmapWindow)(Display*,Window);
 typedef void (* PFN_XUnsetICFocus)(XIC);
 typedef VisualID (* PFN_XVisualIDFromVisual)(Visual*);
@@ -232,7 +231,6 @@ typedef void (* PFN_Xutf8SetWMProperties)(Display*,Window,const char*,const char
 #define XTranslateCoordinates _glfw.x11.xlib.TranslateCoordinates
 #define XUndefineCursor _glfw.x11.xlib.UndefineCursor
 #define XUngrabPointer _glfw.x11.xlib.UngrabPointer
-#define XUnionRectWithRegion _glfw.x11.xlib.UnionRectWithRegion
 #define XUnmapWindow _glfw.x11.xlib.UnmapWindow
 #define XUnsetICFocus _glfw.x11.xlib.UnsetICFocus
 #define XVisualIDFromVisual _glfw.x11.xlib.VisualIDFromVisual
@@ -340,9 +338,12 @@ typedef XRenderPictFormat* (* PFN_XRenderFindVisualFormat)(Display*,Visual const
 typedef Bool (* PFN_XShapeQueryExtension)(Display*,int*,int*);
 typedef Status (* PFN_XShapeQueryVersion)(Display*dpy,int*,int*);
 typedef void (* PFN_XShapeCombineRegion)(Display*,Window,int,int,int,Region,int);
+typedef void (* PFN_XShapeCombineMask)(Display*,Window,int,int,int,Pixmap,int);
+
 #define XShapeQueryExtension _glfw.x11.xshape.QueryExtension
 #define XShapeQueryVersion _glfw.x11.xshape.QueryVersion
 #define XShapeCombineRegion _glfw.x11.xshape.ShapeCombineRegion
+#define XShapeCombineMask _glfw.x11.xshape.ShapeCombineMask
 
 typedef VkFlags VkXlibSurfaceCreateFlagsKHR;
 typedef VkFlags VkXcbSurfaceCreateFlagsKHR;
@@ -596,7 +597,6 @@ typedef struct _GLFWlibraryX11
         PFN_XTranslateCoordinates TranslateCoordinates;
         PFN_XUndefineCursor UndefineCursor;
         PFN_XUngrabPointer UngrabPointer;
-        PFN_XUnionRectWithRegion UnionRectWithRegion;
         PFN_XUnmapWindow UnmapWindow;
         PFN_XUnsetICFocus UnsetICFocus;
         PFN_XVisualIDFromVisual VisualIDFromVisual;
@@ -746,6 +746,7 @@ typedef struct _GLFWlibraryX11
         PFN_XShapeQueryExtension QueryExtension;
         PFN_XShapeCombineRegion ShapeCombineRegion;
         PFN_XShapeQueryVersion QueryVersion;
+        PFN_XShapeCombineMask ShapeCombineMask;
     } xshape;
 
 } _GLFWlibraryX11;
diff --git a/src/x11_window.c b/src/x11_window.c
index bbbff0d5..566dfae0 100644
--- a/src/x11_window.c
+++ b/src/x11_window.c
@@ -2710,21 +2710,19 @@ void _glfwPlatformSetWindowMousePassthrough(_GLFWwindow* window, GLFWbool enable
     if (enabled == window->mousePassthrough)
         return;
 
-    int width = 0;
-    int height = 0;
-    if (!enabled)
-        _glfwPlatformGetWindowSize(window, &width, &height);
+    if (enabled)
+    {
+        Region region = XCreateRegion();
+        XShapeCombineRegion(_glfw.x11.display, window->x11.handle,
+                            2/*ShapeInput*/, 0, 0, region, 0/*ShapeSet*/);
+        XDestroyRegion(region);
+    }
+    else
+    {
+        XShapeCombineMask(_glfw.x11.display, window->x11.handle,
+                          2/*ShapeInput*/, 0, 0, None, 0/*ShapeSet*/);
+    }
 
-    XRectangle rect;
-    rect.x = 0;
-    rect.y = 0;
-    rect.width = (unsigned short)width;
-    rect.height = (unsigned short)height;
-
-    Region region = XCreateRegion();
-    XUnionRectWithRegion(&rect, region, region);
-    XShapeCombineRegion(_glfw.x11.display, window->x11.handle, 2/*ShapeInput*/, 0, 0, region, 0/*ShapeSet*/);
-    XDestroyRegion(region);
     window->mousePassthrough = enabled;
 }