diff --git a/login.php b/login.php
index 67f844bf..9f81e665 100644
--- a/login.php
+++ b/login.php
@@ -368,6 +368,20 @@ function _addAnchor($url, $type, $vars, $url_anchor = null)
 } catch (Horde_Exception $e) {
 }
 
+// IMP declares extra login params (e.g. server selector) via the
+// 'loginparams' auth capability. Merge these independently of the
+// primary Horde auth driver.
+try {
+    $impAuth = $injector->getInstance('Horde_Core_Factory_Auth')->create('imp');
+    if ($impAuth->hasCapability('loginparams')) {
+        $impResult = $impAuth->getLoginParams();
+        $loginparams = array_filter(array_merge($loginparams, $impResult['params'] ?? []));
+        $js_code = array_merge($js_code, $impResult['js_code'] ?? []);
+        $js_files = array_merge($js_files, $impResult['js_files'] ?? []);
+    }
+} catch (\Throwable $e) {
+}
+
 /* If we currently are authenticated, and are not trying to authenticate to
  * an application, redirect to initial page. This is done in index.php.
  * If we are trying to authenticate to an application, but don't have to,
diff --git a/src/Service/LoginService.php b/src/Service/LoginService.php
index c8b1c5af..0c21e923 100644
--- a/src/Service/LoginService.php
+++ b/src/Service/LoginService.php
@@ -114,6 +114,23 @@ public function buildLoginFormData(
             // No backend-specific params
         }
 
+        // IMP declares extra login params (e.g. server selector) via the
+        // 'loginparams' auth capability. Merge these independently of the
+        // primary Horde auth driver, so the server list still appears when
+        // Horde authenticates via LDAP/etc. rather than the 'application'
+        // driver pointed at IMP.
+        try {
+            $impAuth = $this->injector->getInstance('Horde_Core_Factory_Auth')->create('imp');
+            if ($impAuth->hasCapability('loginparams')) {
+                $impResult = $impAuth->getLoginParams();
+                $loginparams = array_filter(array_merge($loginparams, $impResult['params'] ?? []));
+                $jsCode = array_merge($jsCode, $impResult['js_code'] ?? []);
+                $jsFiles = array_merge($jsFiles, $impResult['js_files'] ?? []);
+            }
+        } catch (\Throwable $e) {
+            // IMP not installed, or no extra login params
+        }
+
         // Mode selector
         $modeSelector = '';
         if (!empty($this->conf['user']['select_view'])) {