diff -r 7470985f3fb6 -r 5707cfb531ee src/Tools/VSCode/src/build_vscode.scala
--- a/src/Tools/VSCode/src/build_vscode.scala	Thu Jun 29 23:05:33 2017 +0200
+++ b/src/Tools/VSCode/src/build_vscode.scala	Thu Jun 29 23:05:58 2017 +0200
@@ -36,7 +36,10 @@
     progress.echo(output_path.implode)
 
     progress.bash(
-      "npm install && npm update --dev && vsce " + (if (publish) "publish" else "package"),
+      "npm install && npm update --dev && vsce " +
+      (if (publish)
+        "publish --baseImagesUrl http://isabelle.in.tum.de/repos/isabelle/raw-file/tip/src/Tools/VSCode/extension"
+       else "package"),
       cwd = extension_dir.file, echo = true).check
   }