diff --git a/tests/CanonicalTrait.php b/tests/CanonicalTrait.php
index 971cb66..0e1ee94 100644
--- a/tests/CanonicalTrait.php
+++ b/tests/CanonicalTrait.php
@@ -4,9 +4,6 @@
 
 use ParagonIE\ConstantTime\Binary;
 
-/**
- * @method getNextChar(string $c): string
- */
 trait CanonicalTrait
 {
     public function canonicalDataProvider(): array
@@ -21,6 +18,8 @@ public function canonicalDataProvider(): array
         ];
     }
 
+    abstract protected function getNextChar(string $c): string;
+
     protected function increment(string $str): string
     {
         $i = Binary::safeStrlen($str) - 1;