diff --git a/src/backend/regex/regc_lex.c b/src/backend/regex/regc_lex.c
index 45727ffa01f..4780d79f097 100644
--- a/src/backend/regex/regc_lex.c
+++ b/src/backend/regex/regc_lex.c
@@ -201,6 +201,8 @@ next(struct vars *v)
 {
 	chr			c;
 
+next_restart:					/* loop here after eating a comment */
+
 	/* errors yield an infinite sequence of failures */
 	if (ISERR())
 		return 0;				/* the error has set nexttype to EOS */
@@ -493,8 +495,7 @@ next(struct vars *v)
 						if (!ATEOS())
 							v->now++;
 						assert(v->nexttype == v->lasttype);
-						return next(v);
-						break;
+						goto next_restart;
 					case CHR('='):	/* positive lookahead */
 						NOTE(REG_ULOOKAROUND);
 						RETV(LACON, LATYPE_AHEAD_POS);
diff --git a/src/backend/tsearch/spell.c b/src/backend/tsearch/spell.c
index f07321b61df..edd2fbbd3a5 100644
--- a/src/backend/tsearch/spell.c
+++ b/src/backend/tsearch/spell.c
@@ -63,6 +63,7 @@
 #include "postgres.h"
 
 #include "catalog/pg_collation.h"
+#include "miscadmin.h"
 #include "tsearch/dicts/spell.h"
 #include "tsearch/ts_locale.h"
 #include "utils/memutils.h"
@@ -2400,6 +2401,9 @@ SplitToVariants(IspellDict *Conf, SPNode *snode, SplitVar *orig, char *word, int
 	char	   *notprobed;
 	int			compoundflag = 0;
 
+	/* since this function recurses, it could be driven to stack overflow */
+	check_stack_depth();
+
 	notprobed = (char *) palloc(wordlen);
 	memset(notprobed, 1, wordlen);
 	var = CopyVar(orig, 1);
diff --git a/src/backend/utils/adt/geo_ops.c b/src/backend/utils/adt/geo_ops.c
index b79705f8b3f..535301a2180 100644
--- a/src/backend/utils/adt/geo_ops.c
+++ b/src/backend/utils/adt/geo_ops.c
@@ -3833,6 +3833,9 @@ lseg_inside_poly(Point *a, Point *b, POLYGON *poly, int start)
 	bool		res = true,
 				intersection = false;
 
+	/* since this function recurses, it could be driven to stack overflow */
+	check_stack_depth();
+
 	t.p[0] = *a;
 	t.p[1] = *b;
 	s.p[0] = poly->p[(start == 0) ? (poly->npts - 1) : (start - 1)];
diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c
index 65a57fc3c46..2d3aaaaf6bd 100644
--- a/src/backend/utils/adt/like_support.c
+++ b/src/backend/utils/adt/like_support.c
@@ -44,6 +44,7 @@
 #include "catalog/pg_statistic.h"
 #include "catalog/pg_type.h"
 #include "mb/pg_wchar.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/supportnodes.h"
@@ -1364,6 +1365,9 @@ regex_selectivity_sub(const char *patt, int pattlen, bool case_insensitive)
 	int			paren_pos = 0;	/* dummy init to keep compiler quiet */
 	int			pos;
 
+	/* since this function recurses, it could be driven to stack overflow */
+	check_stack_depth();
+
 	for (pos = 0; pos < pattlen; pos++)
 	{
 		if (patt[pos] == '(')