diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 3b0324ce18..4982fc7eb1 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -943,7 +943,7 @@ cache_locale_time(void)
 }
 
 
-#if defined(WIN32) && defined(LC_MESSAGES)
+#if defined(WIN32)
 /*
  * Convert a Windows setlocale() argument to a Unix-style one.
  *
@@ -1692,6 +1692,16 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 		 */
 		NLSVERSIONINFOEX version = {sizeof(NLSVERSIONINFOEX)};
 		WCHAR		wide_collcollate[LOCALE_NAME_MAX_LENGTH];
+		char	   *shortlocale = IsoLocaleName(collcollate);
+		char	   *underscore;
+
+		/*
+		 * GetNLSVersionEx wants <language>-<REGION> format, whereas the ISO
+		 * format is <language>_<REGION>.  So replace the _ with -
+		 */
+		underscore = strchr(shortlocale, '_');
+		if (underscore)
+			*underscore = '-';
 
 		/* These would be invalid arguments, but have no version. */
 		if (pg_strcasecmp("c", collcollate) == 0 ||
@@ -1699,12 +1709,12 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 			return NULL;
 
 		/* For all other names, ask the OS. */
-		MultiByteToWideChar(CP_ACP, 0, collcollate, -1, wide_collcollate,
+		MultiByteToWideChar(CP_ACP, 0, shortlocale, -1, wide_collcollate,
 							LOCALE_NAME_MAX_LENGTH);
 		if (!GetNLSVersionEx(COMPARE_STRING, wide_collcollate, &version))
 			ereport(ERROR,
 					(errmsg("could not get collation version for locale \"%s\": error code %lu",
-							collcollate,
+							shortlocale,
 							GetLastError())));
 		collversion = psprintf("%d.%d,%d.%d",
 							   (version.dwNLSVersion >> 8) & 0xFFFF,