--- qt-everywhere-src-5.15.16.old/qtbase/src/gui/opengl/qopenglext.h
+++ qt-everywhere-src-5.15.16/qtbase/src/gui/opengl/qopenglext.h
@@ -474,8 +474,8 @@
 typedef signed long long int GLsizeiptr;
 typedef signed long long int GLintptr;
 #else
-typedef signed long int      GLsizeiptr;
-typedef signed long int      GLintptr;
+typedef ptrdiff_t GLsizeiptr;
+typedef ptrdiff_t GLintptr;
 #endif
 
 #define GL_BUFFER_SIZE                    0x8764