diff --git a/configure b/configure
index 6e9ae2689b211b82832e7af5f60f50839f27d3b1..9a7c7849f011b4bef473415111a9211d494a408a 100755
--- a/configure
+++ b/configure
@@ -12650,7 +12650,7 @@ fi
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-for ac_func in cbrt dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate pstat pthread_is_threaded_np readlink setproctitle setsid shm_open symlink sync_file_range towlower utime utimes wcstombs wcstombs_l
+for ac_func in cbrt dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate pstat pthread_is_threaded_np readlink setproctitle setsid shm_open symlink sync_file_range towlower uselocale utime utimes wcstombs wcstombs_l
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
@@ -13404,6 +13404,17 @@ 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$ac_cv_func__configthreadlocale" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE__CONFIGTHREADLOCALE 1
+_ACEOF
+
+fi
+done
+
   ac_fn_c_check_func "$LINENO" "gettimeofday" "ac_cv_func_gettimeofday"
 if test "x$ac_cv_func_gettimeofday" = xyes; then :
   $as_echo "#define HAVE_GETTIMEOFDAY 1" >>confdefs.h
diff --git a/configure.in b/configure.in
index 86fbdff8d44c7e10e44c5bf772a1d787756ab650..ecebc16dbcd0143b6f80197b2ccf5109a6751753 100644
--- a/configure.in
+++ b/configure.in
@@ -1503,7 +1503,32 @@ PGAC_FUNC_WCSTOMBS_L
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-AC_CHECK_FUNCS([cbrt dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate pstat pthread_is_threaded_np readlink setproctitle setsid shm_open symlink sync_file_range towlower utime utimes wcstombs wcstombs_l])
+AC_CHECK_FUNCS(m4_normalize([
+	cbrt
+	dlopen
+	fdatasync
+	getifaddrs
+	getpeerucred
+	getrlimit
+	mbstowcs_l
+	memmove
+	poll
+	posix_fallocate
+	pstat
+	pthread_is_threaded_np
+	readlink
+	setproctitle
+	setsid
+	shm_open
+	symlink
+	sync_file_range
+	towlower
+	uselocale
+	utime
+	utimes
+	wcstombs
+	wcstombs_l
+]))
 
 AC_REPLACE_FUNCS(fseeko)
 case $host_os in
@@ -1667,6 +1692,7 @@ fi
 
 # Win32 (really MinGW) support
 if test "$PORTNAME" = "win32"; then
+  AC_CHECK_FUNCS(_configthreadlocale)
   AC_REPLACE_FUNCS(gettimeofday)
   AC_LIBOBJ(dirmod)
   AC_LIBOBJ(kill)
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index b81b0670d657a6c08220026b5a0a6e6dd210f057..639c18ab57933d4eca3e014698aba474e6f46abe 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -650,6 +650,9 @@
 /* Define to 1 if the system has the type `unsigned long long int'. */
 #undef HAVE_UNSIGNED_LONG_LONG_INT
 
+/* Define to 1 if you have the `uselocale' function. */
+#undef HAVE_USELOCALE
+
 /* Define to 1 if you have the `utime' function. */
 #undef HAVE_UTIME
 
@@ -707,6 +710,9 @@
 /* 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/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index b704b460b011cf656c8a414400e3a38ab962d5ef..b32bc5df1ed941922261401562364135c2c9eb9c 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -497,6 +497,9 @@
 /* Define to 1 if you have the `unsetenv' function. */
 /* #undef HAVE_UNSETENV */
 
+/* Define to 1 if you have the `uselocale' function. */
+/* #undef HAVE_USELOCALE */
+
 /* Define to 1 if you have the `utime' function. */
 #define HAVE_UTIME 1
 
@@ -539,6 +542,9 @@
 /* Define to 1 if your compiler understands __builtin_unreachable. */
 /* #undef HAVE__BUILTIN_UNREACHABLE */
 
+/* Define to 1 if you have the `_configthreadlocale' function. */
+#define HAVE__CONFIGTHREADLOCALE 1
+
 /* Define to 1 if you have __cpuid. */
 #define HAVE__CPUID 1
 
diff --git a/src/interfaces/ecpg/ecpglib/descriptor.c b/src/interfaces/ecpg/ecpglib/descriptor.c
index 899656107833731a203b873f490adbbdb815a511..3caeff5806d405bb33229ed3bf9c1197bd668c73 100644
--- a/src/interfaces/ecpg/ecpglib/descriptor.c
+++ b/src/interfaces/ecpg/ecpglib/descriptor.c
@@ -482,22 +482,45 @@ ECPGget_desc(int lineno, const char *desc_name, int index,...)
 	if (data_var.type != ECPGt_EORT)
 	{
 		struct statement stmt;
-		char	   *oldlocale;
+
+		memset(&stmt, 0, sizeof stmt);
+		stmt.lineno = lineno;
 
 		/* Make sure we do NOT honor the locale for numeric input */
 		/* since the database gives the standard decimal point */
-		oldlocale = ecpg_strdup(setlocale(LC_NUMERIC, NULL), lineno);
+		/* (see comments in execute.c) */
+#ifdef HAVE_USELOCALE
+		stmt.clocale = newlocale(LC_NUMERIC_MASK, "C", (locale_t) 0);
+		if (stmt.clocale != (locale_t) 0)
+			stmt.oldlocale = uselocale(stmt.clocale);
+#else
+#ifdef HAVE__CONFIGTHREADLOCALE
+		stmt.oldthreadlocale = _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
+#endif
+		stmt.oldlocale = ecpg_strdup(setlocale(LC_NUMERIC, NULL), lineno);
 		setlocale(LC_NUMERIC, "C");
-
-		memset(&stmt, 0, sizeof stmt);
-		stmt.lineno = lineno;
+#endif
 
 		/* desperate try to guess something sensible */
 		stmt.connection = ecpg_get_connection(NULL);
 		ecpg_store_result(ECPGresult, index, &stmt, &data_var);
 
-		setlocale(LC_NUMERIC, oldlocale);
-		ecpg_free(oldlocale);
+#ifdef HAVE_USELOCALE
+		if (stmt.oldlocale != (locale_t) 0)
+			uselocale(stmt.oldlocale);
+		if (stmt.clocale)
+			freelocale(stmt.clocale);
+#else
+		if (stmt.oldlocale)
+		{
+			setlocale(LC_NUMERIC, stmt.oldlocale);
+			ecpg_free(stmt.oldlocale);
+		}
+#ifdef HAVE__CONFIGTHREADLOCALE
+		if (stmt.oldthreadlocale != -1)
+			_configthreadlocale(stmt.oldthreadlocale);
+#endif
+#endif
 	}
 	else if (data_var.ind_type != ECPGt_NO_INDICATOR && data_var.ind_pointer != NULL)
 
diff --git a/src/interfaces/ecpg/ecpglib/execute.c b/src/interfaces/ecpg/ecpglib/execute.c
index 5b32e7cbcb2187e6e3874b9c1ffa1230005ef893..266b961eba1044d1d41c1c2ec4a802d274ef51fe 100644
--- a/src/interfaces/ecpg/ecpglib/execute.c
+++ b/src/interfaces/ecpg/ecpglib/execute.c
@@ -104,7 +104,12 @@ free_statement(struct statement * stmt)
 	free_variable(stmt->outlist);
 	ecpg_free(stmt->command);
 	ecpg_free(stmt->name);
+#ifdef HAVE_USELOCALE
+	if (stmt->clocale)
+		freelocale(stmt->clocale);
+#else
 	ecpg_free(stmt->oldlocale);
+#endif
 	ecpg_free(stmt);
 }
 
@@ -1779,8 +1784,32 @@ ecpg_do_prologue(int lineno, const int compat, const int force_indicator,
 
 	/*
 	 * Make sure we do NOT honor the locale for numeric input/output since the
-	 * database wants the standard decimal point
+	 * database wants the standard decimal point.  If available, use
+	 * uselocale() for this because it's thread-safe.  Windows doesn't have
+	 * that, but it usually does have _configthreadlocale().
 	 */
+#ifdef HAVE_USELOCALE
+	stmt->clocale = newlocale(LC_NUMERIC_MASK, "C", (locale_t) 0);
+	if (stmt->clocale == (locale_t) 0)
+	{
+		ecpg_do_epilogue(stmt);
+		return false;
+	}
+	stmt->oldlocale = uselocale(stmt->clocale);
+	if (stmt->oldlocale == (locale_t) 0)
+	{
+		ecpg_do_epilogue(stmt);
+		return false;
+	}
+#else
+#ifdef HAVE__CONFIGTHREADLOCALE
+	stmt->oldthreadlocale = _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
+	if (stmt->oldthreadlocale == -1)
+	{
+		ecpg_do_epilogue(stmt);
+		return false;
+	}
+#endif
 	stmt->oldlocale = ecpg_strdup(setlocale(LC_NUMERIC, NULL), lineno);
 	if (stmt->oldlocale == NULL)
 	{
@@ -1788,6 +1817,7 @@ ecpg_do_prologue(int lineno, const int compat, const int force_indicator,
 		return false;
 	}
 	setlocale(LC_NUMERIC, "C");
+#endif
 
 #ifdef ENABLE_THREAD_SAFETY
 	ecpg_pthreads_init();
@@ -1990,8 +2020,18 @@ ecpg_do_epilogue(struct statement * stmt)
 	if (stmt == NULL)
 		return;
 
+#ifdef HAVE_USELOCALE
+	if (stmt->oldlocale != (locale_t) 0)
+		uselocale(stmt->oldlocale);
+#else
 	if (stmt->oldlocale)
+	{
 		setlocale(LC_NUMERIC, stmt->oldlocale);
+#ifdef HAVE__CONFIGTHREADLOCALE
+		_configthreadlocale(stmt->oldthreadlocale);
+#endif
+	}
+#endif
 
 	free_statement(stmt);
 }
diff --git a/src/interfaces/ecpg/ecpglib/extern.h b/src/interfaces/ecpg/ecpglib/extern.h
index c3082beb4a3abfea2f8fec4f16577888c7427a7a..2af7f0cb8b5b1ea7bb31fd36f1999a2221f14370 100644
--- a/src/interfaces/ecpg/ecpglib/extern.h
+++ b/src/interfaces/ecpg/ecpglib/extern.h
@@ -12,6 +12,9 @@
 #ifndef CHAR_BIT
 #include <limits.h>
 #endif
+#ifdef LOCALE_T_IN_XLOCALE
+#include <xlocale.h>
+#endif
 
 enum COMPAT_MODE
 {
@@ -60,7 +63,15 @@ struct statement
 	bool		questionmarks;
 	struct variable *inlist;
 	struct variable *outlist;
+#ifdef HAVE_USELOCALE
+	locale_t	clocale;
+	locale_t	oldlocale;
+#else
 	char	   *oldlocale;
+#ifdef HAVE__CONFIGTHREADLOCALE
+	int			oldthreadlocale;
+#endif
+#endif
 	int			nparams;
 	char	  **paramvalues;
 	PGresult   *results;