diff --git a/NEWS b/NEWS
index ad480774cc5ad..e9b1eecd6bc34 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,10 @@ PHP                                                                        NEWS
   . Fix crashes when trying to instantiate uninstantiable classes via date
     static constructors. (ndossche)
 
+- Intl:
+  . Fixed bug GH-20426 (Spoofchecker::setRestrictionLevel() error message
+    suggests missing constants). (DanielEScherzer)
+
 - Opcache:
   . Fixed bug GH-20329 (opcache.file_cache broken with full interned string
     buffer). (Arnaud)
diff --git a/ext/intl/spoofchecker/spoofchecker_main.c b/ext/intl/spoofchecker/spoofchecker_main.c
index e168dc16c846b..81b3b40fcf231 100644
--- a/ext/intl/spoofchecker/spoofchecker_main.c
+++ b/ext/intl/spoofchecker/spoofchecker_main.c
@@ -154,8 +154,8 @@ PHP_METHOD(Spoofchecker, setRestrictionLevel)
 			USPOOF_MINIMALLY_RESTRICTIVE != level &&
 			USPOOF_UNRESTRICTIVE != level) {
 		zend_argument_value_error(1, "must be one of Spoofchecker::ASCII, Spoofchecker::SINGLE_SCRIPT_RESTRICTIVE, "
-			"Spoofchecker::SINGLE_HIGHLY_RESTRICTIVE, Spoofchecker::SINGLE_MODERATELY_RESTRICTIVE, "
-			"Spoofchecker::SINGLE_MINIMALLY_RESTRICTIVE, or Spoofchecker::UNRESTRICTIVE");
+			"Spoofchecker::HIGHLY_RESTRICTIVE, Spoofchecker::MODERATELY_RESTRICTIVE, "
+			"Spoofchecker::MINIMALLY_RESTRICTIVE, or Spoofchecker::UNRESTRICTIVE");
 		RETURN_THROWS();
 	}
 
diff --git a/ext/intl/tests/spoofchecker_unknown_restriction_level.phpt b/ext/intl/tests/spoofchecker_unknown_restriction_level.phpt
index e8ed48d60a3eb..6b7e9474755de 100644
--- a/ext/intl/tests/spoofchecker_unknown_restriction_level.phpt
+++ b/ext/intl/tests/spoofchecker_unknown_restriction_level.phpt
@@ -20,4 +20,4 @@ try {
 
 ?>
 --EXPECT--
-Spoofchecker::setRestrictionLevel(): Argument #1 ($level) must be one of Spoofchecker::ASCII, Spoofchecker::SINGLE_SCRIPT_RESTRICTIVE, Spoofchecker::SINGLE_HIGHLY_RESTRICTIVE, Spoofchecker::SINGLE_MODERATELY_RESTRICTIVE, Spoofchecker::SINGLE_MINIMALLY_RESTRICTIVE, or Spoofchecker::UNRESTRICTIVE
+Spoofchecker::setRestrictionLevel(): Argument #1 ($level) must be one of Spoofchecker::ASCII, Spoofchecker::SINGLE_SCRIPT_RESTRICTIVE, Spoofchecker::HIGHLY_RESTRICTIVE, Spoofchecker::MODERATELY_RESTRICTIVE, Spoofchecker::MINIMALLY_RESTRICTIVE, or Spoofchecker::UNRESTRICTIVE