diff --git a/src/JsonSchema/Constraints/UndefinedConstraint.php b/src/JsonSchema/Constraints/UndefinedConstraint.php
index aaf714dd..8effd4ba 100644
--- a/src/JsonSchema/Constraints/UndefinedConstraint.php
+++ b/src/JsonSchema/Constraints/UndefinedConstraint.php
@@ -151,7 +151,7 @@ protected function validateCommonProperties(&$value, $schema, JsonPointer $path,
                     );
                 }
             } else {
-                // If the value is both undefined and not required, skip remaining checks
+                // if the value is both undefined and not required, skip remaining checks
                 // in this method which assume an actual, defined instance when validating.
                 if ($value instanceof self) {
                     return;