diff --git a/apachesolr_search.module b/apachesolr_search.module
index 292cf8b..a9df362 100644
--- a/apachesolr_search.module
+++ b/apachesolr_search.module
@@ -559,6 +559,12 @@ function apachesolr_search_load_all_search_pages() {
 
   $search_pages = $search_pages + $search_pages_db;
 
+  // Ensure that the core search page uses the default environment. In some
+  // instances, for example when unit testing, this search page isn't defined.
+  if (isset($search_pages['core_search'])) {
+    $search_pages['core_search']['env_id'] = apachesolr_default_environment();
+  }
+
   // convert settings to an array
   foreach ($search_pages as $id => $search_page) {
     if (is_string($search_pages[$id]['settings'])) {