diff --git a/test/integration/test_utils.mjs b/test/integration/test_utils.mjs
index f3d949e6a..09a7dcd9d 100644
--- a/test/integration/test_utils.mjs
+++ b/test/integration/test_utils.mjs
@@ -53,9 +53,11 @@ function loadAndWait(filename, selector, zoom, setups, options, viewport) {
           app_options += `&${key}=${encodeURIComponent(value)}`;
         }
       }
-      const url = `${
-        global.integrationBaseUrl
-      }?file=/test/pdfs/${filename}#zoom=${zoom ?? "page-fit"}${app_options}`;
+
+      const fileParam = filename.startsWith("http")
+        ? filename
+        : `/test/pdfs/${filename}`;
+      const url = `${global.integrationBaseUrl}?file=${fileParam}#zoom=${zoom ?? "page-fit"}${app_options}`;
 
       if (setups) {
         // page.evaluateOnNewDocument allows us to run code before the
diff --git a/test/integration/viewer_spec.mjs b/test/integration/viewer_spec.mjs
index 507d15c41..f2eed67ab 100644
--- a/test/integration/viewer_spec.mjs
+++ b/test/integration/viewer_spec.mjs
@@ -1244,4 +1244,33 @@ describe("PDF viewer", () => {
       );
     });
   });
+
+  describe("File param with an URL", () => {
+    let pages;
+
+    beforeEach(async () => {
+      const baseURL = new URL(global.integrationBaseUrl);
+      const url = `${baseURL.origin}/build/generic/web/compressed.tracemonkey-pldi-09.pdf`;
+      pages = await loadAndWait(
+        encodeURIComponent(url),
+        ".textLayer .endOfContent"
+      );
+    });
+
+    afterEach(async () => {
+      await closePages(pages);
+    });
+
+    it("must load and extract the filename correctly", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          const filename = await page.evaluate(() => document.title);
+
+          expect(filename)
+            .withContext(`In ${browserName}`)
+            .toBe("compressed.tracemonkey-pldi-09.pdf");
+        })
+      );
+    });
+  });
 });
diff --git a/web/app.js b/web/app.js
index 5978a5afc..bd8cf0068 100644
--- a/web/app.js
+++ b/web/app.js
@@ -727,7 +727,11 @@ const PDFViewerApplication = {
       const queryString = document.location.search.substring(1);
       const params = parseQueryString(queryString);
       file = params.get("file") ?? AppOptions.get("defaultUrl");
-      file = encodeURIComponent(file).replaceAll("%2F", "/");
+      try {
+        file = new URL(decodeURIComponent(file)).href;
+      } catch {
+        file = encodeURIComponent(file).replaceAll("%2F", "/");
+      }
       validateFileURL(file);
     } else if (PDFJSDev.test("MOZCENTRAL")) {
       file = window.location.href;