Index: src/bin/initdb/initdb.c
===================================================================
--- src/bin/initdb/initdb.c	(HEAD)
+++ src/bin/initdb/initdb.c	(working copy)
@@ -2413,6 +2413,7 @@
 								 * environment */
 	char		bin_dir[MAXPGPATH];
 	char	   *pg_data_native;
+	bool		is_default_locale;
 
 #ifdef WIN32
 	char	   *restrict_env;
@@ -2760,6 +2761,15 @@
 	check_input(features_file);
 	check_input(system_views_file);
 
+	is_default_locale =
+		strlen(locale) == 0 &&
+		strlen(lc_collate) == 0 &&
+		strlen(lc_ctype) == 0 &&
+		strlen(lc_messages) == 0 &&
+		strlen(lc_monetary) == 0 &&
+		strlen(lc_numeric) == 0 &&
+		strlen(lc_time) == 0;
+
 	setlocales();
 
 	printf(_("The files belonging to this database system will be owned "
@@ -2767,29 +2777,6 @@
 			 "This user must also own the server process.\n\n"),
 		   effective_user);
 
-	if (strcmp(lc_ctype, lc_collate) == 0 &&
-		strcmp(lc_ctype, lc_time) == 0 &&
-		strcmp(lc_ctype, lc_numeric) == 0 &&
-		strcmp(lc_ctype, lc_monetary) == 0 &&
-		strcmp(lc_ctype, lc_messages) == 0)
-		printf(_("The database cluster will be initialized with locale %s.\n"), lc_ctype);
-	else
-	{
-		printf(_("The database cluster will be initialized with locales\n"
-				 "  COLLATE:  %s\n"
-				 "  CTYPE:    %s\n"
-				 "  MESSAGES: %s\n"
-				 "  MONETARY: %s\n"
-				 "  NUMERIC:  %s\n"
-				 "  TIME:     %s\n"),
-			   lc_collate,
-			   lc_ctype,
-			   lc_messages,
-			   lc_monetary,
-			   lc_numeric,
-			   lc_time);
-	}
-
 	if (strlen(encoding) == 0)
 	{
 		int		ctype_enc;
@@ -2810,6 +2797,19 @@
 		}
 		else if (!PG_VALID_BE_ENCODING(ctype_enc))
 		{
+			if (is_default_locale)
+			{
+				/*
+				 * We don't support the default locale encoding.
+				 * Use UTF-8 and C locale instead.
+				 */
+				ctype_enc = PG_UTF8;
+				locale = lc_collate = lc_ctype = lc_monetary =
+					lc_numeric = lc_time = lc_messages = "C";
+				setlocales();
+			}
+			else
+			{
 			/* We recognized it, but it's not a legal server encoding */
 			fprintf(stderr,
 					_("%s: locale %s requires unsupported encoding %s\n"),
@@ -2819,13 +2819,11 @@
 					  "Rerun %s with a different locale selection.\n"),
 					pg_encoding_to_char(ctype_enc), progname);
 			exit(1);
+			}
 		}
-		else
-		{
 			encodingid = encodingid_to_string(ctype_enc);
 			printf(_("The default database encoding has accordingly been set to %s.\n"),
 				   pg_encoding_to_char(ctype_enc));
-		}
 	}
 	else
 	{
@@ -2856,6 +2854,29 @@
 		}
 	}
 
+	if (strcmp(lc_ctype, lc_collate) == 0 &&
+		strcmp(lc_ctype, lc_time) == 0 &&
+		strcmp(lc_ctype, lc_numeric) == 0 &&
+		strcmp(lc_ctype, lc_monetary) == 0 &&
+		strcmp(lc_ctype, lc_messages) == 0)
+		printf(_("The database cluster will be initialized with locale %s.\n"), lc_ctype);
+	else
+	{
+		printf(_("The database cluster will be initialized with locales\n"
+				 "  COLLATE:  %s\n"
+				 "  CTYPE:    %s\n"
+				 "  MESSAGES: %s\n"
+				 "  MONETARY: %s\n"
+				 "  NUMERIC:  %s\n"
+				 "  TIME:     %s\n"),
+			   lc_collate,
+			   lc_ctype,
+			   lc_messages,
+			   lc_monetary,
+			   lc_numeric,
+			   lc_time);
+	}
+
 	if (strlen(default_text_search_config) == 0)
 	{
 		default_text_search_config = find_matching_ts_config(lc_ctype);