diff --git a/lib/analyze-action.js b/lib/analyze-action.js
index 301c3cf89..a2835e664 100644
--- a/lib/analyze-action.js
+++ b/lib/analyze-action.js
@@ -89182,14 +89182,13 @@ Error Response: ${JSON.stringify(error4.response, null, 2)}`
   }
 }
 function getDiffRanges(fileDiff, logger) {
-  const filename = path5.join(getRequiredInput("checkout_path"), fileDiff.filename).replaceAll(path5.sep, "/");
   if (fileDiff.patch === void 0) {
     if (fileDiff.changes === 0) {
       return [];
     }
     return [
       {
-        path: filename,
+        path: fileDiff.filename,
         startLine: 0,
         endLine: 0
       }
@@ -89213,7 +89212,7 @@ function getDiffRanges(fileDiff, logger) {
     }
     if (additionRangeStartLine !== void 0) {
       diffRanges.push({
-        path: filename,
+        path: fileDiff.filename,
         startLine: additionRangeStartLine,
         endLine: currentLine - 1
       });
@@ -91333,15 +91332,11 @@ extensions:
       checkPresence: false
     data:
 `;
-  let data = ranges.map(
-    (range) => (
-      // Using yaml.dump() with `forceQuotes: true` ensures that all special
-      // characters are escaped, and that the path is always rendered as a
-      // quoted string on a single line.
-      `      - [${dump(range.path, { forceQuotes: true }).trim()}, ${range.startLine}, ${range.endLine}]
-`
-    )
-  ).join("");
+  let data = ranges.map((range) => {
+    const filename = path12.join(getRequiredInput("checkout_path"), range.path).replaceAll(path12.sep, "/");
+    return `      - [${dump(filename, { forceQuotes: true }).trim()}, ${range.startLine}, ${range.endLine}]
+`;
+  }).join("");
   if (!data) {
     data = '      - ["", 0, 0]\n';
   }
@@ -93651,7 +93646,6 @@ function filterAlertsByDiffRange(logger, sarif) {
   if (!diffRanges?.length) {
     return sarif;
   }
-  const checkoutPath = getRequiredInput("checkout_path");
   for (const run2 of sarif.runs) {
     if (run2.results) {
       run2.results = run2.results.filter((result) => {
@@ -93665,9 +93659,8 @@ function filterAlertsByDiffRange(logger, sarif) {
           if (!locationUri || locationStartLine === void 0) {
             return false;
           }
-          const locationPath = path14.join(checkoutPath, locationUri).replaceAll(path14.sep, "/");
           return diffRanges.some(
-            (range) => range.path === locationPath && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
+            (range) => range.path === locationUri && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
           );
         });
       });
diff --git a/lib/init-action-post.js b/lib/init-action-post.js
index 9696cb4b1..8f76418e6 100644
--- a/lib/init-action-post.js
+++ b/lib/init-action-post.js
@@ -90452,8 +90452,8 @@ var require_primordials = __commonJS({
       ArrayPrototypeIndexOf(self2, el) {
         return self2.indexOf(el);
       },
-      ArrayPrototypeJoin(self2, sep4) {
-        return self2.join(sep4);
+      ArrayPrototypeJoin(self2, sep3) {
+        return self2.join(sep3);
       },
       ArrayPrototypeMap(self2, fn) {
         return self2.map(fn);
@@ -102340,7 +102340,7 @@ var require_commonjs16 = __commonJS({
        *
        * @internal
        */
-      constructor(cwd = process.cwd(), pathImpl, sep4, { nocase, childrenCacheSize = 16 * 1024, fs: fs17 = defaultFS } = {}) {
+      constructor(cwd = process.cwd(), pathImpl, sep3, { nocase, childrenCacheSize = 16 * 1024, fs: fs17 = defaultFS } = {}) {
         this.#fs = fsFromOption(fs17);
         if (cwd instanceof URL || cwd.startsWith("file://")) {
           cwd = (0, node_url_1.fileURLToPath)(cwd);
@@ -102351,7 +102351,7 @@ var require_commonjs16 = __commonJS({
         this.#resolveCache = new ResolveCache();
         this.#resolvePosixCache = new ResolveCache();
         this.#children = new ChildrenCache(childrenCacheSize);
-        const split = cwdPath.substring(this.rootPath.length).split(sep4);
+        const split = cwdPath.substring(this.rootPath.length).split(sep3);
         if (split.length === 1 && !split[0]) {
           split.pop();
         }
@@ -127560,7 +127560,6 @@ function filterAlertsByDiffRange(logger, sarif) {
   if (!diffRanges?.length) {
     return sarif;
   }
-  const checkoutPath = getRequiredInput("checkout_path");
   for (const run2 of sarif.runs) {
     if (run2.results) {
       run2.results = run2.results.filter((result) => {
@@ -127574,9 +127573,8 @@ function filterAlertsByDiffRange(logger, sarif) {
           if (!locationUri || locationStartLine === void 0) {
             return false;
           }
-          const locationPath = path13.join(checkoutPath, locationUri).replaceAll(path13.sep, "/");
           return diffRanges.some(
-            (range) => range.path === locationPath && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
+            (range) => range.path === locationUri && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
           );
         });
       });
diff --git a/lib/upload-lib.js b/lib/upload-lib.js
index 69195cc16..5adb64d05 100644
--- a/lib/upload-lib.js
+++ b/lib/upload-lib.js
@@ -90616,7 +90616,6 @@ function filterAlertsByDiffRange(logger, sarif) {
   if (!diffRanges?.length) {
     return sarif;
   }
-  const checkoutPath = getRequiredInput("checkout_path");
   for (const run of sarif.runs) {
     if (run.results) {
       run.results = run.results.filter((result) => {
@@ -90630,9 +90629,8 @@ function filterAlertsByDiffRange(logger, sarif) {
           if (!locationUri || locationStartLine === void 0) {
             return false;
           }
-          const locationPath = path10.join(checkoutPath, locationUri).replaceAll(path10.sep, "/");
           return diffRanges.some(
-            (range) => range.path === locationPath && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
+            (range) => range.path === locationUri && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
           );
         });
       });
diff --git a/lib/upload-sarif-action.js b/lib/upload-sarif-action.js
index 54af287ba..731d59b2b 100644
--- a/lib/upload-sarif-action.js
+++ b/lib/upload-sarif-action.js
@@ -91085,7 +91085,6 @@ function filterAlertsByDiffRange(logger, sarif) {
   if (!diffRanges?.length) {
     return sarif;
   }
-  const checkoutPath = getRequiredInput("checkout_path");
   for (const run2 of sarif.runs) {
     if (run2.results) {
       run2.results = run2.results.filter((result) => {
@@ -91099,9 +91098,8 @@ function filterAlertsByDiffRange(logger, sarif) {
           if (!locationUri || locationStartLine === void 0) {
             return false;
           }
-          const locationPath = path11.join(checkoutPath, locationUri).replaceAll(path11.sep, "/");
           return diffRanges.some(
-            (range) => range.path === locationPath && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
+            (range) => range.path === locationUri && (range.startLine <= locationStartLine && range.endLine >= locationStartLine || range.startLine === 0 && range.endLine === 0)
           );
         });
       });
diff --git a/src/analyze.test.ts b/src/analyze.test.ts
index 33278271a..97b7d9567 100644
--- a/src/analyze.test.ts
+++ b/src/analyze.test.ts
@@ -4,6 +4,7 @@ import * as path from "path";
 import test from "ava";
 import * as sinon from "sinon";
 
+import * as actionsUtil from "./actions-util";
 import { CodeQuality, CodeScanning } from "./analyses";
 import {
   runQueries,
@@ -161,9 +162,13 @@ test("addSarifExtension", (t) => {
 });
 
 test("diffRangeExtensionPackContents", (t) => {
+  sinon
+    .stub(actionsUtil, "getRequiredInput")
+    .withArgs("checkout_path")
+    .returns("/checkout/path");
   const output = diffRangeExtensionPackContents([
     {
-      path: "/checkout/path/main.js",
+      path: "main.js",
       startLine: 10,
       endLine: 20,
     },
diff --git a/src/analyze.ts b/src/analyze.ts
index 40a637568..6d48ea6fd 100644
--- a/src/analyze.ts
+++ b/src/analyze.ts
@@ -5,7 +5,11 @@ import { performance } from "perf_hooks";
 import * as io from "@actions/io";
 import * as yaml from "js-yaml";
 
-import { getTemporaryDirectory, PullRequestBranches } from "./actions-util";
+import {
+  getTemporaryDirectory,
+  getRequiredInput,
+  PullRequestBranches,
+} from "./actions-util";
 import * as analyses from "./analyses";
 import { setupCppAutobuild } from "./autobuild";
 import { type CodeQL } from "./codeql";
@@ -257,14 +261,22 @@ extensions:
 `;
 
   let data = ranges
-    .map(
-      (range) =>
-        // Using yaml.dump() with `forceQuotes: true` ensures that all special
-        // characters are escaped, and that the path is always rendered as a
-        // quoted string on a single line.
-        `      - [${yaml.dump(range.path, { forceQuotes: true }).trim()}, ` +
-        `${range.startLine}, ${range.endLine}]\n`,
-    )
+    .map((range) => {
+      // Diff-informed queries expect the file path to be absolute. CodeQL always
+      // uses forward slashes as the path separator, so on Windows we need to
+      // replace any backslashes with forward slashes.
+      const filename = path
+        .join(getRequiredInput("checkout_path"), range.path)
+        .replaceAll(path.sep, "/");
+
+      // Using yaml.dump() with `forceQuotes: true` ensures that all special
+      // characters are escaped, and that the path is always rendered as a
+      // quoted string on a single line.
+      return (
+        `      - [${yaml.dump(filename, { forceQuotes: true }).trim()}, ` +
+        `${range.startLine}, ${range.endLine}]\n`
+      );
+    })
     .join("");
   if (!data) {
     // Ensure that the data extension is not empty, so that a pull request with
diff --git a/src/diff-informed-analysis-utils.test.ts b/src/diff-informed-analysis-utils.test.ts
index eeb06cd1b..e9bfdc8e9 100644
--- a/src/diff-informed-analysis-utils.test.ts
+++ b/src/diff-informed-analysis-utils.test.ts
@@ -188,10 +188,6 @@ test(
 );
 
 function runGetDiffRanges(changes: number, patch: string[] | undefined): any {
-  sinon
-    .stub(actionsUtil, "getRequiredInput")
-    .withArgs("checkout_path")
-    .returns("/checkout/path");
   return exportedForTesting.getDiffRanges(
     {
       filename: "test.txt",
@@ -211,7 +207,7 @@ test("getDiffRanges: file diff too large", async (t) => {
   const diffRanges = runGetDiffRanges(1000000, undefined);
   t.deepEqual(diffRanges, [
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 0,
       endLine: 0,
     },
@@ -232,7 +228,7 @@ test("getDiffRanges: diff thunk with single addition range", async (t) => {
   ]);
   t.deepEqual(diffRanges, [
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 53,
       endLine: 54,
     },
@@ -268,7 +264,7 @@ test("getDiffRanges: diff thunk with single update range", async (t) => {
   ]);
   t.deepEqual(diffRanges, [
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 53,
       endLine: 53,
     },
@@ -290,12 +286,12 @@ test("getDiffRanges: diff thunk with addition ranges", async (t) => {
   ]);
   t.deepEqual(diffRanges, [
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 53,
       endLine: 53,
     },
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 55,
       endLine: 55,
     },
@@ -322,12 +318,12 @@ test("getDiffRanges: diff thunk with mixed ranges", async (t) => {
   ]);
   t.deepEqual(diffRanges, [
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 54,
       endLine: 54,
     },
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 57,
       endLine: 58,
     },
@@ -357,12 +353,12 @@ test("getDiffRanges: multiple diff thunks", async (t) => {
   ]);
   t.deepEqual(diffRanges, [
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 53,
       endLine: 54,
     },
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 153,
       endLine: 154,
     },
@@ -373,7 +369,7 @@ test("getDiffRanges: no diff context lines", async (t) => {
   const diffRanges = runGetDiffRanges(2, ["@@ -30 +50,2 @@", "+1", "+2"]);
   t.deepEqual(diffRanges, [
     {
-      path: "/checkout/path/test.txt",
+      path: "test.txt",
       startLine: 50,
       endLine: 51,
     },
diff --git a/src/diff-informed-analysis-utils.ts b/src/diff-informed-analysis-utils.ts
index 4f3a89d9f..8d385146a 100644
--- a/src/diff-informed-analysis-utils.ts
+++ b/src/diff-informed-analysis-utils.ts
@@ -191,13 +191,6 @@ function getDiffRanges(
   fileDiff: FileDiff,
   logger: Logger,
 ): DiffThunkRange[] | undefined {
-  // Diff-informed queries expect the file path to be absolute. CodeQL always
-  // uses forward slashes as the path separator, so on Windows we need to
-  // replace any backslashes with forward slashes.
-  const filename = path
-    .join(actionsUtil.getRequiredInput("checkout_path"), fileDiff.filename)
-    .replaceAll(path.sep, "/");
-
   if (fileDiff.patch === undefined) {
     if (fileDiff.changes === 0) {
       // There are situations where a changed file legitimately has no diff.
@@ -212,7 +205,7 @@ function getDiffRanges(
     // to a special diff range that covers the entire file.
     return [
       {
-        path: filename,
+        path: fileDiff.filename,
         startLine: 0,
         endLine: 0,
       },
@@ -247,7 +240,7 @@ function getDiffRanges(
       // Any line that does not start with a "+" or "-" terminates the current
       // range of added lines.
       diffRanges.push({
-        path: filename,
+        path: fileDiff.filename,
         startLine: additionRangeStartLine,
         endLine: currentLine - 1,
       });
diff --git a/src/upload-lib.test.ts b/src/upload-lib.test.ts
index 02af997be..10138d5ae 100644
--- a/src/upload-lib.test.ts
+++ b/src/upload-lib.test.ts
@@ -6,7 +6,6 @@ import { HTTPError } from "@actions/tool-cache";
 import test from "ava";
 import * as sinon from "sinon";
 
-import * as actionsUtil from "./actions-util";
 import * as analyses from "./analyses";
 import { AnalysisKind, CodeQuality, CodeScanning } from "./analyses";
 import * as api from "./api-client";
@@ -972,10 +971,6 @@ function runFilterAlertsByDiffRange(
   input: SarifFile,
   diffRanges: diffUtils.DiffThunkRange[],
 ): SarifFile {
-  sinon
-    .stub(actionsUtil, "getRequiredInput")
-    .withArgs("checkout_path")
-    .returns("/checkout/path");
   sinon.stub(diffUtils, "readDiffRangesJsonFile").returns(diffRanges);
   return uploadLib.filterAlertsByDiffRange(getRunnerLogger(true), input);
 }
@@ -986,7 +981,7 @@ test("filterAlertsByDiffRange filters out alerts outside diff-range", (t) => {
   );
   const actualOutput = runFilterAlertsByDiffRange(input, [
     {
-      path: "/checkout/path/main.js",
+      path: "main.js",
       startLine: 1,
       endLine: 3,
     },
diff --git a/src/upload-lib.ts b/src/upload-lib.ts
index 01fd5bded..e2ab99d38 100644
--- a/src/upload-lib.ts
+++ b/src/upload-lib.ts
@@ -1143,8 +1143,6 @@ export function filterAlertsByDiffRange(
     return sarif;
   }
 
-  const checkoutPath = actionsUtil.getRequiredInput("checkout_path");
-
   for (const run of sarif.runs) {
     if (run.results) {
       run.results = run.results.filter((result) => {
@@ -1159,11 +1157,6 @@ export function filterAlertsByDiffRange(
           if (!locationUri || locationStartLine === undefined) {
             return false;
           }
-          // CodeQL always uses forward slashes as the path separator, so on Windows we
-          // need to replace any backslashes with forward slashes.
-          const locationPath = path
-            .join(checkoutPath, locationUri)
-            .replaceAll(path.sep, "/");
           // Alert filtering here replicates the same behavior as the restrictAlertsTo
           // extensible predicate in CodeQL. See the restrictAlertsTo documentation
           // https://codeql.github.com/codeql-standard-libraries/csharp/codeql/util/AlertFiltering.qll/predicate.AlertFiltering$restrictAlertsTo.3.html
@@ -1171,7 +1164,7 @@ export function filterAlertsByDiffRange(
           // of an alert location.
           return diffRanges.some(
             (range) =>
-              range.path === locationPath &&
+              range.path === locationUri &&
               ((range.startLine <= locationStartLine &&
                 range.endLine >= locationStartLine) ||
                 (range.startLine === 0 && range.endLine === 0)),