diff --git a/phpBB/docs/sphinx.sample.conf b/phpBB/docs/sphinx.sample.conf
index eaef081aa1..3ab2552096 100644
--- a/phpBB/docs/sphinx.sample.conf
+++ b/phpBB/docs/sphinx.sample.conf
@@ -15,7 +15,7 @@ source source_phpbb_{SPHINX_ID}_main
 							p.forum_id,
\
 							p.topic_id,
\
 							p.poster_id,
\
-							IF(p.post_id = t.topic_first_post_id, 1, 0) as topic_first_post,
\
+							CASE WHEN p.post_id = t.topic_first_post_id THEN 1 ELSE 0 END as topic_first_post,
\
 							p.post_time,
\
 							p.post_subject,
\
 							p.post_subject as title,
\
@@ -47,7 +47,7 @@ source source_phpbb_{SPHINX_ID}_delta : source_phpbb_{SPHINX_ID}_main
 							p.forum_id,
\
 							p.topic_id,
\
 							p.poster_id,
\
-							IF(p.post_id = t.topic_first_post_id, 1, 0) as topic_first_post,
\
+							CASE WHEN p.post_id = t.topic_first_post_id THEN 1 ELSE 0 END as topic_first_post,
\
 							p.post_time,
\
 							p.post_subject,
\
 							p.post_subject as title,
\
diff --git a/phpBB/includes/search/fulltext_sphinx.php b/phpBB/includes/search/fulltext_sphinx.php
index c223284c72..f505703c09 100644
--- a/phpBB/includes/search/fulltext_sphinx.php
+++ b/phpBB/includes/search/fulltext_sphinx.php
@@ -159,7 +159,7 @@ class phpbb_search_fulltext_sphinx
 						p.forum_id,
 						p.topic_id,
 						p.poster_id,
-						IF(p.post_id = t.topic_first_post_id, 1, 0) as topic_first_post,
+						CASE WHEN p.post_id = t.topic_first_post_id THEN 1 ELSE 0 END as topic_first_post,
 						p.post_time,
 						p.post_subject,
 						p.post_subject as title,
@@ -191,7 +191,7 @@ class phpbb_search_fulltext_sphinx
 						p.forum_id,
 						p.topic_id,
 						p.poster_id,
-						IF(p.post_id = t.topic_first_post_id, 1, 0) as topic_first_post,
+						CASE WHEN p.post_id = t.topic_first_post_id THEN 1 ELSE 0 END as topic_first_post,
 						p.post_time,
 						p.post_subject,
 						p.post_subject as title,