diff --git a/dom/base/nsObjectLoadingContent.cpp b/dom/base/nsObjectLoadingContent.cpp
index 6f43a37f4434..acc2feb523f1 100644
--- a/dom/base/nsObjectLoadingContent.cpp
+++ b/dom/base/nsObjectLoadingContent.cpp
@@ -2023,6 +2023,9 @@ void nsObjectLoadingContent::UnloadObject(bool aResetState) {
 
   // This call should be last as it may re-enter
   StopPluginInstance();
+
+  mSubdocumentIntrinsicSize.reset();
+  mSubdocumentIntrinsicRatio.reset();
 }
 
 void nsObjectLoadingContent::NotifyStateChanged(ObjectType aOldType,
diff --git a/testing/web-platform/tests/html/semantics/embedded-content/the-embed-element/embed-svg-navigation-resets-size.html b/testing/web-platform/tests/html/semantics/embedded-content/the-embed-element/embed-svg-navigation-resets-size.html
new file mode 100644
index 000000000000..237c9c3646bb
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/embedded-content/the-embed-element/embed-svg-navigation-resets-size.html
@@ -0,0 +1,31 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>Intrinsic sizing of SVG embedded via &lt;embed&gt; should disappear on navigation</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<embed id="element" name="embed" src='data:image/svg+xml,
+  <svg xmlns="http://www.w3.org/2000/svg"
+       xmlns:xlink="http://www.w3.org/1999/xlink"
+       viewBox="0 0 1000 1000"
+       width="400"
+       height="400"
+       font-size="100">
+  </svg>'></embed>
+<script>
+promise_test(async () => {
+  await new Promise(resolve => {
+    onload = resolve;
+  });
+
+  assert_equals(element.scrollWidth, 400, "The width should be determined by the embedded SVG");
+  assert_equals(element.scrollHeight, 400, "The height should be determined by the embedded SVG");
+
+  await new Promise(resolve => {
+    element.onload = resolve;
+    element.src = "about:blank";
+  });
+
+  assert_equals(element.scrollWidth, 300, "The width should be the default");
+  assert_equals(element.scrollHeight, 150, "The height should be the default");
+});
+</script>
