diff --git a/src/TailwindRuntime.php b/src/TailwindRuntime.php
index cd6549d..57fbd26 100644
--- a/src/TailwindRuntime.php
+++ b/src/TailwindRuntime.php
@@ -22,7 +22,7 @@ public function __construct(?CacheInterface $cache = null)
         $this->factory = TailwindMerge::factory()->withCache(new Psr16Cache($cache));
     }
 
-    public function merge(string|array $classes, array $configuration = []): string
+    public function merge(string|array|null $classes, array $configuration = []): string
     {
         return $this->factory
             ->withConfiguration($configuration)
diff --git a/tests/Fixtures/filters/tailwind_merge.test b/tests/Fixtures/filters/tailwind_merge.test
index 0ab093f..143e493 100644
--- a/tests/Fixtures/filters/tailwind_merge.test
+++ b/tests/Fixtures/filters/tailwind_merge.test
@@ -5,6 +5,7 @@
 {{ "block inline"|tailwind_merge }}
 {{ classes|tailwind_merge }}
 {{ "tw-text-red-500 tw-text-blue-500"|tailwind_merge({prefix: 'tw-'}) }}
+{{ null|tailwind_merge }}
 --DATA--
 return [
     'classes' => ['h-10', 'h-20'],
diff --git a/tests/FunctionalTest.php b/tests/FunctionalTest.php
index 9af7a97..2d81ea0 100644
--- a/tests/FunctionalTest.php
+++ b/tests/FunctionalTest.php
@@ -31,4 +31,11 @@ public function testItCanMergeWithConfiguration(): void
 
         $this->assertSame('tw-text-blue-500', $runtime->merge(['tw-text-red-500', 'tw-text-blue-500'], ['prefix' => 'tw-']));
     }
+
+    public function testItWillReturnEmptyStringIfSuppliedNull(): void
+    {
+        $runtime = new TailwindRuntime();
+
+        $this->assertSame('', $runtime->merge(null));
+    }
 }