diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 759ea87966c3..b6502f032042 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -6718,6 +6718,16 @@ nsresult nsContentUtils::GetWebExposedOriginSerialization(nsIURI* aURI,
       return NS_OK;
     }
 
+    if (
+        // Schemes in spec. https://url.spec.whatwg.org/#origin
+        !uri->SchemeIs("http") && !uri->SchemeIs("https") &&
+        !uri->SchemeIs("file") && !uri->SchemeIs("resource") &&
+        // Our own schemes.
+        !uri->SchemeIs("moz-extension")) {
+      aOrigin.AssignLiteral("null");
+      return NS_OK;
+    }
+
     return GetWebExposedOriginSerialization(uri, aOrigin);
   }
 
diff --git a/dom/url/tests/test_unknown_url_origin.html b/dom/url/tests/test_unknown_url_origin.html
index 1c5571e9e4e8..e44e45393c79 100644
--- a/dom/url/tests/test_unknown_url_origin.html
+++ b/dom/url/tests/test_unknown_url_origin.html
@@ -2,7 +2,7 @@
 <html>
 <head>
   <meta charset="utf-8">
-  <title>Test for unknwon URL.origin</title>
+  <title>Test for unknown URL.origin</title>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
@@ -10,7 +10,7 @@
   <script type="application/javascript">
 
   is((new URL("blob:http://foo.com/bar")).origin, "http://foo.com");
-  is((new URL("blob:blob:http://foo.com/bar")).origin, "http://foo.com");
+  is((new URL("blob:blob:http://foo.com/bar")).origin, "null");
 
   </script>
 </body>
diff --git a/testing/web-platform/meta/url/a-element-origin-xhtml.xhtml.ini b/testing/web-platform/meta/url/a-element-origin-xhtml.xhtml.ini
index 15907c1cdcdb..8c1f24445354 100644
--- a/testing/web-platform/meta/url/a-element-origin-xhtml.xhtml.ini
+++ b/testing/web-platform/meta/url/a-element-origin-xhtml.xhtml.ini
@@ -4,15 +4,3 @@
 
   [Parsing origin: <http://!"$&'()*+,-.;=_`{}~/> against <about:blank>]
     expected: FAIL
-
-  [Parsing origin: <blob:blob:https://example.org/> against <about:blank>]
-    expected: FAIL
-
-  [Parsing origin: <blob:ftp://host/path> against <about:blank>]
-    expected: FAIL
-
-  [Parsing origin: <blob:ws://example.org/> against <about:blank>]
-    expected: FAIL
-
-  [Parsing origin: <blob:wss://example.org/> against <about:blank>]
-    expected: FAIL
diff --git a/testing/web-platform/meta/url/a-element-origin.html.ini b/testing/web-platform/meta/url/a-element-origin.html.ini
index 54d576b732cb..a924e087c78a 100644
--- a/testing/web-platform/meta/url/a-element-origin.html.ini
+++ b/testing/web-platform/meta/url/a-element-origin.html.ini
@@ -4,15 +4,3 @@
 
   [Parsing origin: <http://!"$&'()*+,-.;=_`{}~/> against <about:blank>]
     expected: FAIL
-
-  [Parsing origin: <blob:blob:https://example.org/> against <about:blank>]
-    expected: FAIL
-
-  [Parsing origin: <blob:ftp://host/path> against <about:blank>]
-    expected: FAIL
-
-  [Parsing origin: <blob:ws://example.org/> against <about:blank>]
-    expected: FAIL
-
-  [Parsing origin: <blob:wss://example.org/> against <about:blank>]
-    expected: FAIL
diff --git a/testing/web-platform/meta/url/url-origin.any.js.ini b/testing/web-platform/meta/url/url-origin.any.js.ini
index a45cfeb797c0..d1b9ce14a544 100644
--- a/testing/web-platform/meta/url/url-origin.any.js.ini
+++ b/testing/web-platform/meta/url/url-origin.any.js.ini
@@ -5,18 +5,6 @@
   [Origin parsing: <wss://!"$&'()*+,-.;=_`{}~/> without base]
     expected: FAIL
 
-  [Origin parsing: <blob:blob:https://example.org/> without base]
-    expected: FAIL
-
-  [Origin parsing: <blob:ftp://host/path> without base]
-    expected: FAIL
-
-  [Origin parsing: <blob:ws://example.org/> without base]
-    expected: FAIL
-
-  [Origin parsing: <blob:wss://example.org/> without base]
-    expected: FAIL
-
 
 [url-origin.any.worker.html]
   [Origin parsing: <http://!"$&'()*+,-.;=_`{}~/> without base]
@@ -24,15 +12,3 @@
 
   [Origin parsing: <wss://!"$&'()*+,-.;=_`{}~/> without base]
     expected: FAIL
-
-  [Origin parsing: <blob:blob:https://example.org/> without base]
-    expected: FAIL
-
-  [Origin parsing: <blob:ftp://host/path> without base]
-    expected: FAIL
-
-  [Origin parsing: <blob:ws://example.org/> without base]
-    expected: FAIL
-
-  [Origin parsing: <blob:wss://example.org/> without base]
-    expected: FAIL
