diff --git a/src/components/views/elements/DirectorySearchBox.js b/src/components/views/elements/DirectorySearchBox.js
index adca77ff9f..b0931cfe47 100644
--- a/src/components/views/elements/DirectorySearchBox.js
+++ b/src/components/views/elements/DirectorySearchBox.js
@@ -76,7 +76,7 @@ export default class DirectorySearchBox extends React.Component {
         if (!this.input) return false;
 
         // liberal test for things that look like room aliases
-        return /#.+:.+/.test(this.state.value);
+        return /^#.+:.+/.test(this.state.value);
     }
 
     render() {