diff -Naur pywin32-b302-orig/isapi/src/PyExtensionObjects.cpp pywin32-b302/isapi/src/PyExtensionObjects.cpp
--- pywin32-b302-orig/isapi/src/PyExtensionObjects.cpp	2021-10-11 08:09:18 +0800
+++ pywin32-b302/isapi/src/PyExtensionObjects.cpp	2021-10-12 01:02:29 +0800
@@ -802,7 +802,7 @@
 
     BOOL bRes;
     Py_BEGIN_ALLOW_THREADS bRes =
-        ecb->ServerSupportFunction(ecb->ConnID, HSE_REQ_IO_COMPLETION, DoIOCallback, NULL, NULL);
+        ecb->ServerSupportFunction(ecb->ConnID, HSE_REQ_IO_COMPLETION, (LPVOID)DoIOCallback, NULL, NULL);
     Py_END_ALLOW_THREADS if (!bRes) return SetPyECBError("ServerSupportFunction(HSE_REQ_IO_COMPLETION)");
     Py_RETURN_NONE;
 }
diff -Naur pywin32-b302-orig/isapi/src/PyFilterObjects.cpp pywin32-b302/isapi/src/PyFilterObjects.cpp
--- pywin32-b302-orig/isapi/src/PyFilterObjects.cpp	2021-10-11 08:09:18 +0800
+++ pywin32-b302/isapi/src/PyFilterObjects.cpp	2021-10-12 01:02:56 +0800
@@ -305,7 +305,7 @@
         // The Java code passes "\r\n" as first DWORD, and header in second,
         // but docs clearly have second as unused.  Either way, I can't see the
         // specific header!
-        bRes = phfc->m_pfc->ServerSupportFunction(SF_REQ_SEND_RESPONSE_HEADER, status, (DWORD)header, 0);
+        bRes = phfc->m_pfc->ServerSupportFunction(SF_REQ_SEND_RESPONSE_HEADER, status, (DWORD_PTR)header, 0);
     Py_END_ALLOW_THREADS if (!bRes) return SetPyHFCError("SendResponseHeader");
     Py_INCREF(Py_None);
     return Py_None;
diff -Naur pywin32-b302-orig/isapi/src/PythonEng.h pywin32-b302/isapi/src/PythonEng.h
--- pywin32-b302-orig/isapi/src/PythonEng.h	2021-10-11 08:09:18 +0800
+++ pywin32-b302/isapi/src/PythonEng.h	2021-10-12 01:03:08 +0800
@@ -63,7 +63,7 @@
     PyObject *DoCallback(HANDLER_TYPE typ, PyObject *args);
 
     bool LoadHandler(bool reload);
-    bool CPythonHandler::CheckCallback(const char *cbname, PyObject **cb);
+    bool CheckCallback(const char *cbname, PyObject **cb);
     const char *m_namefactory;
     const char *m_nameinit;
     const char *m_namedo;
diff -Naur pywin32-b302-orig/isapi/src/StdAfx.h pywin32-b302/isapi/src/StdAfx.h
--- pywin32-b302-orig/isapi/src/StdAfx.h	2021-10-11 08:09:18 +0800
+++ pywin32-b302/isapi/src/StdAfx.h	2021-10-12 01:04:22 +0800
@@ -45,6 +45,10 @@
 // avoid anyone accidently using the wrong WRITE_RESTRICTED...
 #undef WRITE_RESTRICTED
 
+#ifndef _MSC_VER
+#define HSE_REQ_SET_FLUSH_FLAG (HSE_REQ_END_RESERVED+43)
+#endif
+
 // ***** py3k support *****
 // Note that when built for py3k, 'UNICODE' is defined, which conveniently
 // means TCHAR is the same size as the native unicode object in all versions.