diff --git a/src/zulip.rs b/src/zulip.rs
index c9b2f62f9..cf58cc0cb 100644
--- a/src/zulip.rs
+++ b/src/zulip.rs
@@ -71,7 +71,7 @@ pub struct Request {
 }
 
 #[derive(Clone, Debug, serde::Deserialize)]
-struct Message {
+pub(crate) struct Message {
     id: u64,
     sender_id: u64,
     /// A unique ID for the set of users receiving the message (either a
@@ -375,10 +375,15 @@ async fn handle_command<'a>(
                 StreamCommand::AssignPriority { issue_num, prio } => {
                     let _ = match assign_issue_prio(&ctx, message_data, issue_num, prio).await {
                         // give user feedback
-                        Ok(_) => ctx.zulip.add_reaction(message_data.id, "check").await,
+                        Ok(_) => {
+                            // emoji reaction for the triagebot command
+                            ctx.zulip.add_reaction(message_data.id, "check").await?;
+                            // resolve the Zulip topic
+                            ctx.zulip.resolve_topic(message_data.clone()).await?;
+                        }
                         Err(err) => {
                             log::error!("Could not assign priority to #{}: {:?}", issue_num, err);
-                            ctx.zulip.add_reaction(message_data.id, "scream").await
+                            ctx.zulip.add_reaction(message_data.id, "scream").await?;
                         }
                     };
                     Ok(None)
diff --git a/src/zulip/client.rs b/src/zulip/client.rs
index bb92773b5..5a6c815ba 100644
--- a/src/zulip/client.rs
+++ b/src/zulip/client.rs
@@ -201,6 +201,45 @@ impl ZulipClient {
                 .into()
         })
     }
+
+    // https://zulip.com/api/update-message#parameter-topic
+    pub(crate) async fn resolve_topic(&self, message_data: super::Message) -> anyhow::Result<()> {
+        let message_id = message_data.id;
+        let topic = message_data
+            .subject
+            .unwrap_or_default()
+            .replacen("", "✔ ", 1);
+        #[derive(serde::Serialize)]
+        struct ResolveTopic<'a> {
+            topic: &'a str,
+            propagate_mode: &'a str,
+            send_notification_to_old_thread: bool,
+            send_notification_to_new_thread: bool,
+        }
+
+        let resp = self
+            .make_request(Method::PATCH, &format!("messages/{message_id}"))
+            .form(&ResolveTopic {
+                topic: &topic,
+                propagate_mode: "change_all",
+                send_notification_to_old_thread: false,
+                send_notification_to_new_thread: false,
+            })
+            .send()
+            .await
+            .context("failed to add reaction to a Zulip message")?;
+
+        let status = resp.status();
+        if !status.is_success() {
+            let body = resp
+                .text()
+                .await
+                .context("fail receiving Zulip API response (when adding a reaction)")?;
+            anyhow::bail!(body)
+        }
+
+        Ok(())
+    }
 }
 
 async fn deserialize_response<T>(response: Response) -> anyhow::Result<T>