diff --git a/phpBB/phpbb/search/backend/fulltext_native.php b/phpBB/phpbb/search/backend/fulltext_native.php
index aefc73b8cd..56161d3eb2 100644
--- a/phpBB/phpbb/search/backend/fulltext_native.php
+++ b/phpBB/phpbb/search/backend/fulltext_native.php
@@ -393,7 +393,7 @@ class fulltext_native extends base implements search_backend_interface
 				$word = substr($word, 1);
 
 				// a group of which at least one may not be in the resulting posts
-				if ($word[0] == '(')
+				if (isset($word[0]) && $word[0] == '(')
 				{
 					$word = array_unique(explode('|', substr($word, 1, -1)));
 					$mode = 'must_exclude_one';
diff --git a/tests/functional/search/base.php b/tests/functional/search/base.php
index b66bb5c7a2..b209c21348 100644
--- a/tests/functional/search/base.php
+++ b/tests/functional/search/base.php
@@ -183,6 +183,7 @@ abstract class phpbb_functional_search_base extends phpbb_functional_test_case
 		}
 
 		$this->assert_search_not_found('loremipsumdedo');
+		$this->assert_search_not_found('loremipsumdedo+-'); // test search query ending with the space followed by hyphen
 		$this->assert_search_not_found('barsearch+-testing'); // test excluding keyword
 		$this->assert_search_for_author_not_found('authornotexists');