diff --git a/src/github/utils/image-downloader.ts b/src/github/utils/image-downloader.ts
index 1e819ff..0b2c0c7 100644
--- a/src/github/utils/image-downloader.ts
+++ b/src/github/utils/image-downloader.ts
@@ -1,18 +1,24 @@
 import fs from "fs/promises";
 import path from "path";
 import type { Octokits } from "../api/client";
-import { GITHUB_SERVER_URL } from "../api/config";
 
-const escapedUrl = GITHUB_SERVER_URL.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
-const IMAGE_REGEX = new RegExp(
-  `!\\[[^\\]]*\\]\\((${escapedUrl}\\/user-attachments\\/assets\\/[^)]+)\\)`,
-  "g",
-);
-
-const HTML_IMG_REGEX = new RegExp(
-  `<img[^>]+src=["']([^"']*${escapedUrl}\\/user-attachments\\/assets\\/[^"']+)["'][^>]*>`,
-  "gi",
-);
+// Build regexes at call time, reading GITHUB_SERVER_URL from process.env
+// directly. The config.ts export freezes the value at module load time,
+// which can be wrong when the Forgejo CI runner injects its own
+// GITHUB_SERVER_URL that the shell export cannot override.
+function buildImageRegexes(): { imageRegex: RegExp; htmlImgRegex: RegExp } {
+  const serverUrl = process.env.GITHUB_SERVER_URL || "https://github.com";
+  const escapedUrl = serverUrl.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+  const imageRegex = new RegExp(
+    `!\\[[^\\]]*\\]\\((${escapedUrl}\\/user-attachments\\/assets\\/[^)]+)\\)`,
+    "g",
+  );
+  const htmlImgRegex = new RegExp(
+    `<img[^>]+src=["']([^"']*${escapedUrl}\\/user-attachments\\/assets\\/[^"']+)["'][^>]*>`,
+    "gi",
+  );
+  return { imageRegex, htmlImgRegex };
+}
 
 type IssueComment = {
   type: "issue_comment";
@@ -63,6 +69,8 @@ export async function downloadCommentImages(
 
   await fs.mkdir(downloadsDir, { recursive: true });
 
+  const { imageRegex, htmlImgRegex } = buildImageRegexes();
+
   const commentsWithImages: Array<{
     comment: CommentWithImages;
     urls: string[];
@@ -70,11 +78,11 @@ export async function downloadCommentImages(
 
   for (const comment of comments) {
     // Extract URLs from Markdown format
-    const markdownMatches = [...comment.body.matchAll(IMAGE_REGEX)];
+    const markdownMatches = [...comment.body.matchAll(imageRegex)];
     const markdownUrls = markdownMatches.map((match) => match[1] as string);
 
     // Extract URLs from HTML format
-    const htmlMatches = [...comment.body.matchAll(HTML_IMG_REGEX)];
+    const htmlMatches = [...comment.body.matchAll(htmlImgRegex)];
     const htmlUrls = htmlMatches.map((match) => match[1] as string);
 
     // Combine and deduplicate URLs
diff --git a/test/image-downloader.test.ts b/test/image-downloader.test.ts
index e00b6d0..124413a 100644
--- a/test/image-downloader.test.ts
+++ b/test/image-downloader.test.ts
@@ -20,8 +20,14 @@ describe("downloadCommentImages", () => {
   let fsMkdirSpy: any;
   let fsWriteFileSpy: any;
   let fetchSpy: any;
+  let savedServerUrl: string | undefined;
 
   beforeEach(() => {
+    // Pin GITHUB_SERVER_URL so tests pass regardless of runner environment.
+    // The image-downloader reads process.env directly at call time.
+    savedServerUrl = process.env.GITHUB_SERVER_URL;
+    process.env.GITHUB_SERVER_URL = "https://github.com";
+
     // Spy on console methods
     consoleLogSpy = spyOn(console, "log").mockImplementation(() => {});
     consoleWarnSpy = spyOn(console, "warn").mockImplementation(() => {});
@@ -36,6 +42,13 @@ describe("downloadCommentImages", () => {
   });
 
   afterEach(() => {
+    // Restore GITHUB_SERVER_URL
+    if (savedServerUrl !== undefined) {
+      process.env.GITHUB_SERVER_URL = savedServerUrl;
+    } else {
+      delete process.env.GITHUB_SERVER_URL;
+    }
+
     consoleLogSpy.mockRestore();
     consoleWarnSpy.mockRestore();
     consoleErrorSpy.mockRestore();