diff --git a/configure b/configure
index 199d666aa73..163ef9a7732 100755
--- a/configure
+++ b/configure
@@ -15821,17 +15821,6 @@ fi
 
 # Win32 (really MinGW) support
 if test "$PORTNAME" = "win32"; then
-  for ac_func in _configthreadlocale
-do :
-  ac_fn_c_check_func "$LINENO" "_configthreadlocale" "ac_cv_func__configthreadlocale"
-if test "x$ac_cv_func__configthreadlocale" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE__CONFIGTHREADLOCALE 1
-_ACEOF
-
-fi
-done
-
   case " $LIBOBJS " in
   *" dirmod.$ac_objext "* ) ;;
   *) LIBOBJS="$LIBOBJS dirmod.$ac_objext"
diff --git a/configure.ac b/configure.ac
index 4f56bb5062e..8c3367bd545 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1820,7 +1820,6 @@ fi
 
 # Win32 (really MinGW) support
 if test "$PORTNAME" = "win32"; then
-  AC_CHECK_FUNCS(_configthreadlocale)
   AC_LIBOBJ(dirmod)
   AC_LIBOBJ(kill)
   AC_LIBOBJ(open)
diff --git a/meson.build b/meson.build
index 83e61d0f4a8..ff3848b1d85 100644
--- a/meson.build
+++ b/meson.build
@@ -2617,7 +2617,6 @@ endif
 # XXX: Might be worth conditioning some checks on the OS, to avoid doing
 # unnecessary checks over and over, particularly on windows.
 func_checks = [
-  ['_configthreadlocale', {'skip': host_system != 'windows'}],
   ['backtrace_symbols', {'dependencies': [execinfo_dep]}],
   ['clock_gettime', {'dependencies': [rt_dep], 'define': false}],
   ['copyfile'],
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 40e4b2e3816..6e25afc58fd 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -529,9 +529,6 @@
 /* Define to 1 if your compiler understands __builtin_unreachable. */
 #undef HAVE__BUILTIN_UNREACHABLE
 
-/* Define to 1 if you have the `_configthreadlocale' function. */
-#undef HAVE__CONFIGTHREADLOCALE
-
 /* Define to 1 if you have __cpuid. */
 #undef HAVE__CPUID
 
diff --git a/src/interfaces/ecpg/ecpglib/descriptor.c b/src/interfaces/ecpg/ecpglib/descriptor.c
index ad279e245c4..56e2bc41531 100644
--- a/src/interfaces/ecpg/ecpglib/descriptor.c
+++ b/src/interfaces/ecpg/ecpglib/descriptor.c
@@ -490,7 +490,7 @@ ECPGget_desc(int lineno, const char *desc_name, int index,...)
 		Assert(ecpg_clocale);
 		stmt.oldlocale = uselocale(ecpg_clocale);
 #else
-#ifdef HAVE__CONFIGTHREADLOCALE
+#ifdef WIN32
 		stmt.oldthreadlocale = _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
 #endif
 		stmt.oldlocale = ecpg_strdup(setlocale(LC_NUMERIC, NULL), lineno);
@@ -510,7 +510,7 @@ ECPGget_desc(int lineno, const char *desc_name, int index,...)
 			setlocale(LC_NUMERIC, stmt.oldlocale);
 			ecpg_free(stmt.oldlocale);
 		}
-#ifdef HAVE__CONFIGTHREADLOCALE
+#ifdef WIN32
 		if (stmt.oldthreadlocale != -1)
 			(void) _configthreadlocale(stmt.oldthreadlocale);
 #endif
diff --git a/src/interfaces/ecpg/ecpglib/ecpglib_extern.h b/src/interfaces/ecpg/ecpglib/ecpglib_extern.h
index bad3cd9920b..75cc68275bd 100644
--- a/src/interfaces/ecpg/ecpglib/ecpglib_extern.h
+++ b/src/interfaces/ecpg/ecpglib/ecpglib_extern.h
@@ -77,7 +77,7 @@ struct statement
 	locale_t	oldlocale;
 #else
 	char	   *oldlocale;
-#ifdef HAVE__CONFIGTHREADLOCALE
+#ifdef WIN32
 	int			oldthreadlocale;
 #endif
 #endif
diff --git a/src/interfaces/ecpg/ecpglib/execute.c b/src/interfaces/ecpg/ecpglib/execute.c
index c578c21cf66..466d5600f9b 100644
--- a/src/interfaces/ecpg/ecpglib/execute.c
+++ b/src/interfaces/ecpg/ecpglib/execute.c
@@ -1995,7 +1995,7 @@ ecpg_do_prologue(int lineno, const int compat, const int force_indicator,
 		return false;
 	}
 #else
-#ifdef HAVE__CONFIGTHREADLOCALE
+#ifdef WIN32
 	stmt->oldthreadlocale = _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
 #endif
 	stmt->oldlocale = ecpg_strdup(setlocale(LC_NUMERIC, NULL), lineno);
@@ -2219,7 +2219,7 @@ ecpg_do_epilogue(struct statement *stmt)
 #else
 	if (stmt->oldlocale)
 		setlocale(LC_NUMERIC, stmt->oldlocale);
-#ifdef HAVE__CONFIGTHREADLOCALE
+#ifdef WIN32
 
 	/*
 	 * This is a bit trickier than it looks: if we failed partway through