diff --git a/common/src/app/common/data.cljc b/common/src/app/common/data.cljc
index 70f775b4c3..715bd97544 100644
--- a/common/src/app/common/data.cljc
+++ b/common/src/app/common/data.cljc
@@ -1156,5 +1156,6 @@
 
 (defn append-class
   [class current-class]
-  (str (if (some? class) (str class " ") "")
-       current-class))
+  (if (seq class)
+    (str class " " current-class)
+    current-class))
diff --git a/common/test/common_tests/data_test.cljc b/common/test/common_tests/data_test.cljc
index f0487ed71d..d85e835af9 100644
--- a/common/test/common_tests/data_test.cljc
+++ b/common/test/common_tests/data_test.cljc
@@ -791,7 +791,8 @@
 (t/deftest append-class-test
   (t/is (= "foo bar" (d/append-class "foo" "bar")))
   (t/is (= "bar" (d/append-class nil "bar")))
-  (t/is (= " bar" (d/append-class "" "bar"))))
+  ;; empty string is treated like nil — no leading space
+  (t/is (= "bar" (d/append-class "" "bar"))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Additional helpers (5th batch)