diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 6ff48bb18f3639ae45d9528b32df51a4aebc60c0..07758d15e8613d5a049537ddf2c5992e57ad6424 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1042,11 +1042,16 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 					 errmsg("ICU locale must be specified")));
-	}
 
-	if (dblocprovider == COLLPROVIDER_ICU)
 		check_icu_locale(dbiculocale);
 
+		if (!(is_encoding_supported_by_icu(encoding)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("encoding \"%s\" is not supported with ICU provider",
+							pg_encoding_to_char(encoding))));
+	}
+
 	/*
 	 * Check that the new encoding and locale settings match the source
 	 * database.  We insist on this because we simply copy the source data ---
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index e00837ecacf4885cf2a176168c283f3e67c6eb53..8a762ced8340c9d8256f7832a4c19a43f1d5538a 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2362,6 +2362,16 @@ setup_locale_encoding(void)
 	if (!check_locale_encoding(lc_ctype, encodingid) ||
 		!check_locale_encoding(lc_collate, encodingid))
 		exit(1);				/* check_locale_encoding printed the error */
+
+	if (locale_provider == COLLPROVIDER_ICU &&
+		!(is_encoding_supported_by_icu(encodingid)))
+	{
+		pg_log_error("encoding \"%s\" is not supported with ICU provider",
+					 pg_encoding_to_char(encodingid));
+		pg_log_error_hint("Rerun %s and choose a matching combination.",
+						  progname);
+		exit(1);
+	}
 }
 
 
diff --git a/src/bin/initdb/t/001_initdb.pl b/src/bin/initdb/t/001_initdb.pl
index a37f6dd9b334b6ee22d9fdd4d51422795cb54a39..e4bb3d0cdd9c23729c5fb97886374f8df558f239 100644
--- a/src/bin/initdb/t/001_initdb.pl
+++ b/src/bin/initdb/t/001_initdb.pl
@@ -118,6 +118,15 @@ if ($ENV{with_icu} eq 'yes')
 		],
 		qr/FATAL:  could not open collator for locale/,
 		'fails for invalid ICU locale');
+
+	command_fails_like(
+		[
+			'initdb',                '--no-sync',
+			'--locale-provider=icu', '--icu-locale=en',
+			'--encoding=SQL_ASCII',  "$tempdir/dataX"
+		],
+		qr/error: encoding "SQL_ASCII" is not supported with ICU provider/,
+		'encoding "SQL_ASCII" is not supported with ICU provider');
 }
 else
 {
diff --git a/src/bin/scripts/t/020_createdb.pl b/src/bin/scripts/t/020_createdb.pl
index e91c1d013d08d8bd1e3a92f2aba958c5c7713ca6..eaab3caa32669ead068719d98bb953c5c6ff5a17 100644
--- a/src/bin/scripts/t/020_createdb.pl
+++ b/src/bin/scripts/t/020_createdb.pl
@@ -50,6 +50,16 @@ if ($ENV{with_icu} eq 'yes')
 		],
 		'fails for invalid ICU locale');
 
+	$node->command_fails_like(
+		[
+			'createdb',        '-T',
+			'template0',       '--locale-provider=icu',
+			'--icu-locale=en', '--encoding=SQL_ASCII',
+			'foobarX'
+		],
+		qr/ERROR:  encoding "SQL_ASCII" is not supported with ICU provider/,
+		'encoding "SQL_ASCII" is not supported with ICU provider');
+
 	# additional node, which uses the icu provider
 	my $node2 = PostgreSQL::Test::Cluster->new('icu');
 	$node2->init(extra => ['--locale-provider=icu', '--icu-locale=en']);