diff --git a/src/views/messages-view.jsx b/src/views/messages-view.jsx
index d4b919dd..7664e09a 100644
--- a/src/views/messages-view.jsx
+++ b/src/views/messages-view.jsx
@@ -1654,6 +1654,23 @@ class MessagesView extends React.Component {
       const RISK_RANK = {block: 2, warn: 1, allow: 0};
       const urls = Array.from(new Set(urlMatches));
       return Promise.all(urls.map(url => checkURL(url, 'message_compose'))).then(results => {
+        // The user may have already switched to a different conversation while checkURL was
+        // still in flight. getDerivedStateFromProps only protects against an ALREADY-shown
+        // dialog surviving a later topic switch (it nulls riskDialog when nextProps.topic !=
+        // prevState.topic) -- it can't protect against this .then() running AFTER that switch,
+        // which would otherwise setState({riskDialog:{...}}) fresh right here, popping the risk
+        // dialog up while a completely different conversation is now open. doSend() still calls
+        // this.props.sendMessage using whatever topic is current AT CONFIRM TIME (see doSend's
+        // own comment above), not the one this message was actually typed in, so confirming that
+        // dialog would silently deliver this message into the wrong conversation. Confirmed live:
+        // typed a flagged URL in topic A, switched to topic B before checkURL resolved, and the
+        // resulting dialog rendered while viewing topic B -- confirming it delivered topic A's
+        // message into topic B instead. If the topic has moved on, treat this message the same
+        // as if it were abandoned -- no dialog, no send -- the same "lost, but not hung forever"
+        // outcome already accepted just below for two flagged messages sent in quick succession.
+        if (this.state.topic !== topicForDraft) {
+          return false;
+        }
         const result = results.reduce((worst, r) => (RISK_RANK[r.decision] || 0) > (RISK_RANK[worst.decision] || 0) ? r : worst);
         if (result.decision === 'allow') {
           return doSend();