diff --git a/src/Psalm/Type/ParseTree.php b/src/Psalm/Type/ParseTree.php
index f8048882d..7a45f9737 100644
--- a/src/Psalm/Type/ParseTree.php
+++ b/src/Psalm/Type/ParseTree.php
@@ -465,7 +465,7 @@ class ParseTree
                         case '::':
                             $nexter_token = $i + 2 < $c ? $type_tokens[$i + 2] : null;
 
-                            if (!$nexter_token || !preg_match('/^[A-Z_]+$/', $nexter_token)) {
+                            if (!$nexter_token || !preg_match('/^[A-Z_0-9]+$/', $nexter_token)) {
                                 throw new TypeParseTreeException(
                                     'Invalid class constant ' . $nexter_token
                                 );
diff --git a/tests/EnumTest.php b/tests/EnumTest.php
index 98ef5817c..b8d5ca2d7 100644
--- a/tests/EnumTest.php
+++ b/tests/EnumTest.php
@@ -60,10 +60,10 @@ class EnumTest extends TestCase
                     namespace Ns;
 
                     class C {
-                        const A = "bat";
+                        const A1 = "bat";
                         const B = "baz";
                     }
-                    /** @psalm-param "foo"|"bar"|C::A|C::B $s */
+                    /** @psalm-param "foo"|"bar"|C::A1|C::B $s */
                     function foo($s) : void {}
                     foo("foo");
                     foo("bar");