diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index b73dd65c5f..867f645ccd 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -642,11 +642,13 @@
 
 #if defined(CURL_WINDOWS_UWP) || defined(UNDER_CE)
 #define CURL_THREAD_RETURN_T DWORD
+#define CURL_WIN_THREADFUNC WINAPI
 typedef HANDLE curl_win_thread_handle_t;
 #define CURL_WIN_BEGINTHREAD CreateThread
 #else
 #define CURL_THREAD_RETURN_T unsigned int
 #ifdef _WIN32
+#define CURL_WIN_THREADFUNC __stdcall
 typedef uintptr_t curl_win_thread_handle_t;
 #define CURL_WIN_BEGINTHREAD _beginthreadex
 #endif /* _WIN32 */
diff --git a/lib/curl_threads.h b/lib/curl_threads.h
index 8748cf8b2d..b17a789dd1 100644
--- a/lib/curl_threads.h
+++ b/lib/curl_threads.h
@@ -35,7 +35,7 @@
 #  define Curl_mutex_release(m)  pthread_mutex_unlock(m)
 #  define Curl_mutex_destroy(m)  pthread_mutex_destroy(m)
 #elif defined(USE_THREADS_WIN32)
-#  define CURL_STDCALL           __stdcall
+#  define CURL_STDCALL           CURL_WIN_THREADFUNC
 #  define curl_mutex_t           CRITICAL_SECTION
 #  define curl_thread_t          HANDLE
 #  define curl_thread_t_null     (HANDLE)0
diff --git a/tests/libtest/lib3026.c b/tests/libtest/lib3026.c
index 92d637aa7c..8c36de3dd0 100644
--- a/tests/libtest/lib3026.c
+++ b/tests/libtest/lib3026.c
@@ -27,7 +27,7 @@
 
 #ifdef _WIN32
 #include <process.h>
-static CURL_THREAD_RETURN_T __stdcall t3026_run_thread(void *ptr)
+static CURL_THREAD_RETURN_T CURL_WIN_THREADFUNC t3026_run_thread(void *ptr)
 {
   CURLcode *result = ptr;
 
diff --git a/tests/server/sockfilt.c b/tests/server/sockfilt.c
index a16f032e04..5e57b193e9 100644
--- a/tests/server/sockfilt.c
+++ b/tests/server/sockfilt.c
@@ -413,7 +413,8 @@ struct select_ws_wait_data {
   HANDLE abort;  /* internal event to abort waiting threads */
 };
 #include <process.h>
-static unsigned int WINAPI select_ws_wait_thread(void *lpParameter)
+static
+unsigned int CURL_WIN_THREADFUNC select_ws_wait_thread(void *lpParameter)
 {
   struct select_ws_wait_data *data;
   HANDLE signal, handle, handles[2];
diff --git a/tests/server/util.c b/tests/server/util.c
index 44425f03e4..2ec5dae624 100644
--- a/tests/server/util.c
+++ b/tests/server/util.c
@@ -488,7 +488,8 @@ static LRESULT CALLBACK main_window_proc(HWND hwnd, UINT uMsg,
 /* Window message queue loop for hidden main window, details see above.
  */
 #include <process.h>
-static CURL_THREAD_RETURN_T WINAPI main_window_loop(void *lpParameter)
+static
+CURL_THREAD_RETURN_T CURL_WIN_THREADFUNC main_window_loop(void *lpParameter)
 {
   WNDCLASS wc;
   BOOL ret;