diff --git a/src/utility.lisp b/src/utility.lisp
index f4ddcd2..f97007b 100644
--- a/src/utility.lisp
+++ b/src/utility.lisp
@@ -163,9 +163,11 @@ Example 3:
 Example 4:
   (opacity :level :auto)
   ; This will generate a string 'opacity-auto'"
-  (let ((level-str (if (null level) "" (if (eq level :auto)
-                                           "opacity-auto"
-                                           (format nil "opacity-~d" level)))))
+  (let ((level-str (if (null level)
+                       ""
+                       (if (equal level "auto")
+                           "opacity-auto"
+                           (format nil "opacity-~d" level)))))
     (string-clean (concatenate 'string level-str))))
 
 (defun overflow (&key (direction nil) (value nil))
diff --git a/tests/utility.lisp b/tests/utility.lisp
index 5b7e41f..c44399b 100644
--- a/tests/utility.lisp
+++ b/tests/utility.lisp
@@ -86,7 +86,7 @@
 
 (deftest test-opacity-auto
   (testing "Generates correct opacity class for auto"
-    (ok (string= (opacity :level :auto) "opacity-auto"))))
+    (ok (string= (opacity :level "auto") "opacity-auto"))))
 
 (deftest test-opacity-no-arguments
   (testing "Generates correct opacity class with no arguments"