diff --git a/htmlSanityCheck-core/src/main/java/org/aim42/htmlsanitycheck/check/CheckerCreator.java b/htmlSanityCheck-core/src/main/java/org/aim42/htmlsanitycheck/check/CheckerCreator.java
index 9f9b3297..e5853e50 100644
--- a/htmlSanityCheck-core/src/main/java/org/aim42/htmlsanitycheck/check/CheckerCreator.java
+++ b/htmlSanityCheck-core/src/main/java/org/aim42/htmlsanitycheck/check/CheckerCreator.java
@@ -51,7 +51,7 @@ public static Checker createSingleChecker(final Class<? extends Checker> checker
         } else if (isCase(MissingLocalResourcesChecker.class, checkerClass)) {
             checker = new MissingLocalResourcesChecker(pConfig);
         } else {
-            logger.warn("unknown Checker " + checkerClass.toString());
+            logger.error("unknown Checker {}", checkerClass);
             throw new UnknownCheckerException(checkerClass.toString());
         }