--- CMakeLists.txt.orig	2024-05-30 18:10:10 UTC
+++ CMakeLists.txt
@@ -411,6 +411,10 @@ endif ()
 elseif (ENABLE_STATIC_EXE)
     set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libgcc -static-libstdc++")
 endif ()
+# CMake 3.20 doesn't do the tests internally in TestBigEndian
+# that end up setting HAVE_STDINT_H and similar.
+include(CheckTypeSize)
+CHECK_TYPE_SIZE("unsigned short" CMAKE_SIZEOF_UNSIGNED_SHORT LANGUAGE C)
 
 if (ENABLE_FRAME_POINTER)
     # disable frame pointer omission