diff --git a/contrib/ltree/lquery_op.c b/contrib/ltree/lquery_op.c
index 31d150db40f..8624907573f 100644
--- a/contrib/ltree/lquery_op.c
+++ b/contrib/ltree/lquery_op.c
@@ -8,6 +8,7 @@
 #include <ctype.h>
 
 #include "catalog/pg_collation.h"
+#include "miscadmin.h"
 #include "utils/formatting.h"
 #include "ltree.h"
 
@@ -165,6 +166,12 @@ checkCond(lquery_level *curq, int query_numlevel, ltree_level *curt, int tree_nu
 	lquery_level *prevq = NULL;
 	ltree_level *prevt = NULL;
 
+	/* Since this function recurses, it could be driven to stack overflow */
+	check_stack_depth();
+
+	/* Pathological patterns could take awhile, too */
+	CHECK_FOR_INTERRUPTS();
+
 	if (SomeStack.muse)
 	{
 		high_pos = SomeStack.high_pos;