diff --git a/frontend_tests/node_tests/stream_data.js b/frontend_tests/node_tests/stream_data.js
index af7891d975..b1f5a092c9 100644
--- a/frontend_tests/node_tests/stream_data.js
+++ b/frontend_tests/node_tests/stream_data.js
@@ -992,4 +992,7 @@ test("can_post_messages_in_stream", () => {
 
     social.stream_post_policy = stream_data.stream_post_policy_values.everyone.code;
     assert.equal(stream_data.can_post_messages_in_stream(social), true);
+
+    page_params.is_spectator = true;
+    assert.equal(stream_data.can_post_messages_in_stream(social), false);
 });
diff --git a/static/js/stream_data.js b/static/js/stream_data.js
index 06efc17a9c..847484a38b 100644
--- a/static/js/stream_data.js
+++ b/static/js/stream_data.js
@@ -557,6 +557,10 @@ export function can_subscribe_others(sub) {
 }
 
 export function can_post_messages_in_stream(stream) {
+    if (page_params.is_spectator) {
+        return false;
+    }
+
     if (page_params.is_admin) {
         return true;
     }