diff --git a/dlls/jscript/array.c b/dlls/jscript/array.c
index 65097be4a32..c131865be11 100644
--- a/dlls/jscript/array.c
+++ b/dlls/jscript/array.c
@@ -194,7 +194,23 @@ static void Array_destructor(DispatchEx *dispex)
 
 static void Array_on_put(DispatchEx *dispex, const WCHAR *name)
 {
-    FIXME("\n");
+    ArrayInstance *array = (ArrayInstance*)dispex;
+    const WCHAR *ptr = name;
+    DWORD id = 0;
+
+    if(!isdigitW(*ptr))
+        return;
+
+    while(*ptr && isdigitW(*ptr)) {
+        id = id*10 + (*ptr-'0');
+        ptr++;
+    }
+
+    if(*ptr)
+        return;
+
+    if(id >= array->length)
+        array->length = id+1;
 }
 
 static const builtin_prop_t Array_props[] = {
diff --git a/dlls/jscript/tests/api.js b/dlls/jscript/tests/api.js
index e8740275876..eed48dc2056 100644
--- a/dlls/jscript/tests/api.js
+++ b/dlls/jscript/tests/api.js
@@ -28,6 +28,9 @@ ok(arr["0"] === 1, "arr[0] is not 1");
 ok(arr["1"] === 2, "arr[1] is not 2");
 ok(arr["2"] === "test", "arr[2] is not \"test\"");
 
+arr["7"] = true;
+ok((arr.length === 8), "arr.length is not 8");
+
 var arr = new Array(6);
 ok(typeof(arr) === "object", "arr (6) is not object");
 ok((arr.length === 6), "arr.length is not 6");