diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b42a88c..b1112c03 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 * feat: Transformers now have the option to have an invariant target type.
 * fix: Wrong service id for `CopyTransformer`.
 * fix: Remove cache file & regenerate it if it is corrupt.
+* fix: `NullTransformer` bug.
 
 ## 0.5.8
 
diff --git a/src/Transformer/NullTransformer.php b/src/Transformer/NullTransformer.php
index 6e314392..77a8d96c 100644
--- a/src/Transformer/NullTransformer.php
+++ b/src/Transformer/NullTransformer.php
@@ -54,7 +54,11 @@ public function transform(
             return [];
         }
 
-        throw new InvalidArgumentException(sprintf('Target must be scalar, "%s" given', get_debug_type($targetType)), context: $context);
+        if (TypeCheck::isNull($targetType)) {
+            return null;
+        }
+
+        throw new InvalidArgumentException(sprintf('Target must be scalar, "%s" given.', get_debug_type($targetType)), context: $context);
     }
 
     public function getSupportedTransformation(): iterable