diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -516,7 +516,7 @@
     'rsrc/js/phui/behavior-phui-timer-control.js' => 'f84bcbf4',
     'rsrc/js/phuix/PHUIXActionListView.js' => 'c68f183f',
     'rsrc/js/phuix/PHUIXActionView.js' => 'aaa08f3b',
-    'rsrc/js/phuix/PHUIXAutocomplete.js' => '8f139ef0',
+    'rsrc/js/phuix/PHUIXAutocomplete.js' => '2fbe234d',
     'rsrc/js/phuix/PHUIXButtonView.js' => '55a24e84',
     'rsrc/js/phuix/PHUIXDropdownMenu.js' => 'bdce4d78',
     'rsrc/js/phuix/PHUIXExample.js' => 'c2c500a7',
@@ -872,7 +872,7 @@
     'phui-workpanel-view-css' => '3ae89b20',
     'phuix-action-list-view' => 'c68f183f',
     'phuix-action-view' => 'aaa08f3b',
-    'phuix-autocomplete' => '8f139ef0',
+    'phuix-autocomplete' => '2fbe234d',
     'phuix-button-view' => '55a24e84',
     'phuix-dropdown-menu' => 'bdce4d78',
     'phuix-form-control-view' => '38c1f3fb',
@@ -1173,6 +1173,12 @@
       'phuix-autocomplete',
       'javelin-mask',
     ),
+    '2fbe234d' => array(
+      'javelin-install',
+      'javelin-dom',
+      'phuix-icon-view',
+      'phabricator-prefab',
+    ),
     '308f9fe4' => array(
       'javelin-install',
       'javelin-util',
@@ -1634,12 +1640,6 @@
     '8e2d9a28' => array(
       'phui-theme-css',
     ),
-    '8f139ef0' => array(
-      'javelin-install',
-      'javelin-dom',
-      'phuix-icon-view',
-      'phabricator-prefab',
-    ),
     '8f959ad0' => array(
       'javelin-behavior',
       'javelin-dom',
diff --git a/webroot/rsrc/js/phuix/PHUIXAutocomplete.js b/webroot/rsrc/js/phuix/PHUIXAutocomplete.js
--- a/webroot/rsrc/js/phuix/PHUIXAutocomplete.js
+++ b/webroot/rsrc/js/phuix/PHUIXAutocomplete.js
@@ -555,6 +555,13 @@
       if (prefix) {
         var pattern = new RegExp(prefix);
         if (!trim.match(pattern)) {
+          // If the prefix pattern can not match the text, deactivate. (This
+          // check might need to be more careful if we have a more varied
+          // set of prefixes in the future, but for now they're all a single
+          // prefix character.)
+          if (trim.length) {
+            this._deactivate();
+          }
           return;
         }
         trim = trim.replace(pattern, '');