diff --git a/Libraries/LibJS/Runtime/ArrayPrototype.cpp b/Libraries/LibJS/Runtime/ArrayPrototype.cpp
index 4be61e58ab8..b9ff84a0abb 100644
--- a/Libraries/LibJS/Runtime/ArrayPrototype.cpp
+++ b/Libraries/LibJS/Runtime/ArrayPrototype.cpp
@@ -239,7 +239,7 @@ Value ArrayPrototype::join(Interpreter& interpreter)
         return {};
 
     String separator = ",";
-    if (interpreter.argument_count() == 1) {
+    if (interpreter.argument_count()) {
         separator = interpreter.argument(0).to_string(interpreter);
         if (interpreter.exception())
             return {};
diff --git a/Libraries/LibJS/Tests/Array.prototype.join.js b/Libraries/LibJS/Tests/Array.prototype.join.js
index 0221aacfd39..fc82deb20cc 100644
--- a/Libraries/LibJS/Tests/Array.prototype.join.js
+++ b/Libraries/LibJS/Tests/Array.prototype.join.js
@@ -5,6 +5,7 @@ try {
 
     assert(["hello", "friends"].join() === "hello,friends");
     assert(["hello", "friends"].join(" ") === "hello friends");
+    assert(["hello", "friends", "foo"].join("~", "#") === "hello~friends~foo");
     assert([].join() === "");
     assert([null].join() === "");
     assert([undefined].join() === "");