diff --git a/contrib/ltree/_ltree_gist.c b/contrib/ltree/_ltree_gist.c
index 0344b6dc13493fcffc73bf269bfc7b68c96b172b..c4623ec020f02bf657ced33233ed520f435118d7 100644
--- a/contrib/ltree/_ltree_gist.c
+++ b/contrib/ltree/_ltree_gist.c
@@ -76,6 +76,10 @@ _ltree_compress(PG_FUNCTION_ARGS)
 			ereport(ERROR,
 					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
 					 errmsg("array must be one-dimensional")));
+		if (ARR_HASNULL(val))
+			ereport(ERROR,
+					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+					 errmsg("array must not contain nulls")));
 
 		key = (ltree_gist *) palloc(len);
 		key->len = len;
@@ -518,6 +522,10 @@ _arrq_cons(ltree_gist * key, ArrayType *_query)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
 				 errmsg("array must be one-dimensional")));
+	if (ARR_HASNULL(_query))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("array must not contain nulls")));
 
 	while (num > 0)
 	{
diff --git a/contrib/ltree/_ltree_op.c b/contrib/ltree/_ltree_op.c
index 729d19c08292100b3aa536ed73b96bbe9a14f3cd..ff8eec793a644eae571635638aca4c03ed3277ac 100644
--- a/contrib/ltree/_ltree_op.c
+++ b/contrib/ltree/_ltree_op.c
@@ -47,6 +47,10 @@ array_iterator(ArrayType *la, PGCALL2 callback, void *param, ltree ** found)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
 				 errmsg("array must be one-dimensional")));
+	if (ARR_HASNULL(la))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("array must not contain nulls")));
 
 	if (found)
 		*found = NULL;
@@ -143,6 +147,10 @@ _lt_q_regex(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
 				 errmsg("array must be one-dimensional")));
+	if (ARR_HASNULL(_query))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("array must not contain nulls")));
 
 	while (num > 0)
 	{
@@ -293,6 +301,15 @@ _lca(PG_FUNCTION_ARGS)
 	ltree	  **a,
 			   *res;
 
+	if (ARR_NDIM(la) != 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+				 errmsg("array must be one-dimensional")));
+	if (ARR_HASNULL(la))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("array must not contain nulls")));
+
 	a = (ltree **) palloc(sizeof(ltree *) * num);
 	while (num > 0)
 	{
diff --git a/contrib/ltree/lquery_op.c b/contrib/ltree/lquery_op.c
index 54466a5b6beb717f1276c6f9b26ce32e77f5bc06..6d5a937bebba152587a75f368c2a1894c9a51a21 100644
--- a/contrib/ltree/lquery_op.c
+++ b/contrib/ltree/lquery_op.c
@@ -328,6 +328,10 @@ lt_q_regex(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
 				 errmsg("array must be one-dimensional")));
+	if (ARR_HASNULL(_query))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("array must not contain nulls")));
 
 	while (num > 0)
 	{
diff --git a/contrib/ltree/ltree_gist.c b/contrib/ltree/ltree_gist.c
index 2be6449329c71bf0068c7998cb8c400b009bcbe2..9cdbcde886e7a889be9b01d58c9136db333cb7d1 100644
--- a/contrib/ltree/ltree_gist.c
+++ b/contrib/ltree/ltree_gist.c
@@ -607,6 +607,10 @@ arrq_cons(ltree_gist * key, ArrayType *_query)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
 				 errmsg("array must be one-dimensional")));
+	if (ARR_HASNULL(_query))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("array must not contain nulls")));
 
 	while (num > 0)
 	{