diff --git a/lang/ast/expr/arith.c b/lang/ast/expr/arith.c
index c3c1ded..fe49816 100644
--- a/lang/ast/expr/arith.c
+++ b/lang/ast/expr/arith.c
@@ -379,18 +379,28 @@ enum ivy_status expr_finalise_arith(
 		op = op_node->n_op;
 		tmp = b_queue_pop_back(&q);
 		op_node->n_right = b_unbox(struct ivy_ast_node, tmp, n_entry);
-		op_node->n_right->n_parent = (struct ivy_ast_node *)op_node;
-		ivy_ast_node_extend_bounds_recursive(
-			(struct ivy_ast_node *)op_node, (struct ivy_ast_node *)tmp);
+
+		if (op_node->n_right) {
+			op_node->n_right->n_parent = (struct ivy_ast_node *)op_node;
+
+			ivy_ast_node_extend_bounds_recursive(
+				(struct ivy_ast_node *)op_node,
+				(struct ivy_ast_node *)tmp);
+		}
 
 		if (op->op_arity == IVY_OP_BINARY) {
 			tmp = b_queue_pop_back(&q);
 			op_node->n_left
 				= b_unbox(struct ivy_ast_node, tmp, n_entry);
-			op_node->n_left->n_parent = (struct ivy_ast_node *)op_node;
-			ivy_ast_node_extend_bounds_recursive(
-				(struct ivy_ast_node *)op_node,
-				(struct ivy_ast_node *)tmp);
+
+			if (op_node->n_left) {
+				op_node->n_left->n_parent
+					= (struct ivy_ast_node *)op_node;
+
+				ivy_ast_node_extend_bounds_recursive(
+					(struct ivy_ast_node *)op_node,
+					(struct ivy_ast_node *)tmp);
+			}
 		}
 
 		/* ...and push the newly-completed operator node to the operand