1 files changed, 10 insertions, 0 deletions
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index 8f74e146e..15e4936b1 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -542,6 +542,16 @@ function bootstrapMainRuntime(runtimeOptions) {
 
   if (unstableFlag) {
     ObjectAssign(finalDenoNs, denoNsUnstable);
+    // TODO(bartlomieju): this is not ideal, but because we use `ObjectAssign`
+    // above any properties that are defined elsewhere using `Object.defineProperty`
+    // are lost.
+    ObjectDefineProperty(finalDenoNs, "jupyter", {
+      get() {
+        throw new Error(
+          "Deno.jupyter is only available in `deno jupyter` subcommand.",
+        );
+      },
+    });
   }
 
   // Setup `Deno` global - we're actually overriding already existing global