diff --git a/src/server/routes/file-etag.ts b/src/server/routes/file-etag.ts
index 90ad240..a65fe0b 100644
--- a/src/server/routes/file-etag.ts
+++ b/src/server/routes/file-etag.ts
@@ -1,16 +1,20 @@
 import { createHash } from "crypto";
 
-// Build an ETag that fingerprints both the upstream content (?v=<sha>) and
-// the anonymization config the user has saved. Without the config part, the
-// browser kept serving content anonymized under an older term list — see
-// #439 (anonymization "doesn't work" in regular tabs but works in incognito).
+// Build an ETag that fingerprints the upstream content (?v=<sha>), the file
+// path, and the anonymization config the user has saved. Without the config
+// part the browser kept serving bytes anonymized under an older term list
+// (#439). The path is folded in so two different files inside the same repo
+// can never collide.
 export function fileETag(
   versionParam: string | undefined,
+  filePath: string,
   options: unknown
 ): string {
   const h = createHash("sha1");
   h.update(versionParam || "");
   h.update("|");
+  h.update(filePath || "");
+  h.update("|");
   h.update(JSON.stringify(options ?? null));
   return `"f-${h.digest("hex")}"`;
 }
diff --git a/src/server/routes/file.ts b/src/server/routes/file.ts
index 69157d4..7cc1789 100644
--- a/src/server/routes/file.ts
+++ b/src/server/routes/file.ts
@@ -54,6 +54,7 @@ router.get(
       }
       const etag = fileETag(
         req.query.v as string | undefined,
+        anonymizedPath,
         repo.model.options
       );
       res.header("ETag", etag);
diff --git a/test/file-etag.test.js b/test/file-etag.test.js
index ecd78f8..079ac07 100644
--- a/test/file-etag.test.js
+++ b/test/file-etag.test.js
@@ -3,37 +3,50 @@ require("ts-node/register/transpile-only");
 const { fileETag } = require("../src/server/routes/file-etag");
 
 describe("fileETag", function () {
+  const opts = { terms: ["alice"] };
+
   it("changes when the upstream sha changes", function () {
-    const opts = { terms: ["alice"] };
-    expect(fileETag("sha1", opts)).to.not.equal(fileETag("sha2", opts));
+    expect(fileETag("sha1", "README.md", opts)).to.not.equal(
+      fileETag("sha2", "README.md", opts)
+    );
+  });
+
+  it("changes when the file path changes", function () {
+    expect(fileETag("sha1", "README.md", opts)).to.not.equal(
+      fileETag("sha1", "src/index.ts", opts)
+    );
   });
 
   // #439 — without folding the anonymization options into the ETag, editing
   // the term list left the same URL serving stale anonymized bytes.
   it("changes when the anonymization terms change", function () {
-    const a = fileETag("sha1", { terms: ["alice"] });
-    const b = fileETag("sha1", { terms: ["alice", "bob"] });
-    expect(a).to.not.equal(b);
+    expect(fileETag("sha1", "README.md", { terms: ["alice"] })).to.not.equal(
+      fileETag("sha1", "README.md", { terms: ["alice", "bob"] })
+    );
   });
 
   it("changes when an anonymization toggle changes", function () {
-    const a = fileETag("sha1", { terms: ["alice"], image: true });
-    const b = fileETag("sha1", { terms: ["alice"], image: false });
-    expect(a).to.not.equal(b);
+    expect(
+      fileETag("sha1", "README.md", { terms: ["alice"], image: true })
+    ).to.not.equal(
+      fileETag("sha1", "README.md", { terms: ["alice"], image: false })
+    );
   });
 
   it("is stable for the same inputs", function () {
-    const opts = { terms: ["alice", "bob"], image: true };
-    expect(fileETag("sha1", opts)).to.equal(fileETag("sha1", opts));
+    expect(fileETag("sha1", "README.md", opts)).to.equal(
+      fileETag("sha1", "README.md", opts)
+    );
   });
 
   it("treats missing version like an empty string", function () {
-    const opts = { terms: [] };
-    expect(fileETag(undefined, opts)).to.equal(fileETag("", opts));
+    expect(fileETag(undefined, "README.md", { terms: [] })).to.equal(
+      fileETag("", "README.md", { terms: [] })
+    );
   });
 
   it("returns a quoted opaque tag", function () {
-    const tag = fileETag("sha1", { terms: [] });
+    const tag = fileETag("sha1", "README.md", { terms: [] });
     expect(tag).to.match(/^"f-[0-9a-f]{40}"$/);
   });
 });