diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index 0eaab8e58a4..6a4b67a6a92 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -493,6 +493,7 @@ impl HTMLImageElement {
         request.image = None;
         request.metadata = None;
         let document = document_from_node(self);
+        LoadBlocker::terminate(&mut request.blocker);
         request.blocker = Some(LoadBlocker::new(&*document, LoadType::Image(url.clone())));
     }
 
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index e0694fdb2c0..37f08769d33 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -13193,6 +13193,12 @@
      {}
     ]
    ],
+   "mozilla/img_async_src_set_before_window_load.html": [
+    [
+     "/_mozilla/mozilla/img_async_src_set_before_window_load.html",
+     {}
+    ]
+   ],
    "mozilla/img_find_non_sibling_map.html": [
     [
      "/_mozilla/mozilla/img_find_non_sibling_map.html",
@@ -25862,6 +25868,10 @@
    "3c4f36abed83367c851d943b1f25b8394de6fe75",
    "testharness"
   ],
+  "mozilla/img_async_src_set_before_window_load.html": [
+   "c7895fe3b7b7f11a4853760e386e12a08bb51b96",
+   "testharness"
+  ],
   "mozilla/img_find_non_sibling_map.html": [
    "d34100c4cc22adcaa1014095ba4b7b929b8e079d",
    "testharness"
diff --git a/tests/wpt/mozilla/tests/mozilla/img_async_src_set_before_window_load.html b/tests/wpt/mozilla/tests/mozilla/img_async_src_set_before_window_load.html
new file mode 100644
index 00000000000..370d4ef9b8d
--- /dev/null
+++ b/tests/wpt/mozilla/tests/mozilla/img_async_src_set_before_window_load.html
@@ -0,0 +1,15 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Shouldn't panic when setting src attribute on img asynchronously before window.onload.</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<img id="image" src="#">
+<script>
+  async_test(function(t) {
+    image = document.getElementById('image');
+
+    setTimeout(t.step_func_done(function() {
+      image.src = 'test.png';
+    }), 0);
+  }, "Setting src attribute asynchronously on image before window.onload doesn't panic.");
+</script>
