diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index aa759c264861b5e357c47910bf893fafe8ba1224..a165b3b1ca5676973376c13c0ef84f067b5135ec 100644
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -951,7 +951,7 @@ parseqatom(struct vars * v,
 			EMPTYARC(lp, s);
 			EMPTYARC(s2, rp);
 			NOERR();
-			atom = parse(v, ')', PLAIN, s, s2);
+			atom = parse(v, ')', type, s, s2);
 			assert(SEE(')') || ISERR());
 			NEXT();
 			NOERR();
diff --git a/src/test/regress/expected/regex.out b/src/test/regress/expected/regex.out
index f0e2fc9eb896786c3206ad88e68868867be317fe..07fb023534fa576e2b1a0357542c5acc5ce36a63 100644
--- a/src/test/regress/expected/regex.out
+++ b/src/test/regress/expected/regex.out
@@ -490,3 +490,8 @@ select 'a' ~ '()+\1';
  t
 (1 row)
 
+-- Error conditions
+select 'xyz' ~ 'x(\w)(?=\1)';  -- no backrefs in LACONs
+ERROR:  invalid regular expression: invalid backreference number
+select 'xyz' ~ 'x(\w)(?=(\1))';
+ERROR:  invalid regular expression: invalid backreference number
diff --git a/src/test/regress/sql/regex.sql b/src/test/regress/sql/regex.sql
index d3030af295d3852714c2dfa13ea2ca9597ef686d..c45bdc91d853419e2fd094adb4a18f9de1ab8e5e 100644
--- a/src/test/regress/sql/regex.sql
+++ b/src/test/regress/sql/regex.sql
@@ -117,3 +117,7 @@ select 'a' ~ '$()|^\1';
 select 'a' ~ '.. ()|\1';
 select 'a' ~ '()*\1';
 select 'a' ~ '()+\1';
+
+-- Error conditions
+select 'xyz' ~ 'x(\w)(?=\1)';  -- no backrefs in LACONs
+select 'xyz' ~ 'x(\w)(?=(\1))';