diff --git a/jscomp/test/dist/jscomp/test/js_array_test.js b/jscomp/test/dist/jscomp/test/js_array_test.js
index 8521e07c3..c9a8d26f3 100644
--- a/jscomp/test/dist/jscomp/test/js_array_test.js
+++ b/jscomp/test/dist/jscomp/test/js_array_test.js
@@ -600,7 +600,7 @@ var suites_1 = {
                                                                                 1,
                                                                                 2,
                                                                                 3
-                                                                              ].join("")
+                                                                              ].join(",")
                                                                           };
                                                                   })
                                                               ],
diff --git a/jscomp/test/js_array_test.ml b/jscomp/test/js_array_test.ml
index ca6d05902..b31b14c12 100644
--- a/jscomp/test/js_array_test.ml
+++ b/jscomp/test/js_array_test.ml
@@ -160,7 +160,7 @@ let suites = Mt.[
     );
 
     "join", (fun _ ->
-      Eq("1,2,3", [| 1; 2; 3 |] |. Js.Array.join ~sep:"")
+      Eq("1,2,3", [| 1; 2; 3 |] |. Js.Array.join ~sep:",")
     );
     "joinWith", (fun _ ->
       Eq("1;2;3", [| 1; 2; 3 |] |. Js.Array.join ~sep:";")