diff --git a/contrib/pg_trgm/expected/pg_trgm.out b/contrib/pg_trgm/expected/pg_trgm.out
index c3304b0ceb9..6efc54356a1 100644
--- a/contrib/pg_trgm/expected/pg_trgm.out
+++ b/contrib/pg_trgm/expected/pg_trgm.out
@@ -7,6 +7,9 @@ WHERE opc.oid >= 16384 AND NOT amvalidate(opc.oid);
 --------+---------
 (0 rows)
 
+--backslash is used in tests below, installcheck will fail if
+--standard_conforming_string is off
+set standard_conforming_strings=on;
 select show_trgm('');
  show_trgm 
 -----------
diff --git a/contrib/pg_trgm/sql/pg_trgm.sql b/contrib/pg_trgm/sql/pg_trgm.sql
index fe8d0a7495d..96ae542320d 100644
--- a/contrib/pg_trgm/sql/pg_trgm.sql
+++ b/contrib/pg_trgm/sql/pg_trgm.sql
@@ -5,6 +5,10 @@ SELECT amname, opcname
 FROM pg_opclass opc LEFT JOIN pg_am am ON am.oid = opcmethod
 WHERE opc.oid >= 16384 AND NOT amvalidate(opc.oid);
 
+--backslash is used in tests below, installcheck will fail if
+--standard_conforming_string is off
+set standard_conforming_strings=on;
+
 select show_trgm('');
 select show_trgm('(*&^$@%@');
 select show_trgm('a b c');