diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index aa759c2..a165b3b 100644
*** a/src/backend/regex/regcomp.c
--- b/src/backend/regex/regcomp.c
*************** parseqatom(struct vars * v,
*** 951,957 ****
  			EMPTYARC(lp, s);
  			EMPTYARC(s2, rp);
  			NOERR();
! 			atom = parse(v, ')', PLAIN, s, s2);
  			assert(SEE(')') || ISERR());
  			NEXT();
  			NOERR();
--- 951,957 ----
  			EMPTYARC(lp, s);
  			EMPTYARC(s2, rp);
  			NOERR();
! 			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 f0e2fc9..07fb023 100644
*** a/src/test/regress/expected/regex.out
--- b/src/test/regress/expected/regex.out
*************** select 'a' ~ '()+\1';
*** 490,492 ****
--- 490,497 ----
   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 d3030af..c45bdc9 100644
*** a/src/test/regress/sql/regex.sql
--- b/src/test/regress/sql/regex.sql
*************** select 'a' ~ '$()|^\1';
*** 117,119 ****
--- 117,123 ----
  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))';