diff --git a/pg_search/src/lib.rs b/pg_search/src/lib.rs
index be078422a..98394de69 100644
--- a/pg_search/src/lib.rs
+++ b/pg_search/src/lib.rs
@@ -74,6 +74,10 @@ pub fn MyDatabaseId() -> u32 {
 #[allow(non_snake_case)]
 #[pg_guard]
 pub unsafe extern "C" fn _PG_init() {
+    if !pg_sys::process_shared_preload_libraries_in_progress {
+        error!("pg_search must be loaded via shared_preload_libraries. Add 'pg_search' to shared_preload_libraries in postgresql.conf and restart Postgres.");
+    }
+
     postgres::options::init();
     GUCS.init("pg_search");