From 591344ca9df24feadc10db8cd8a6e37252cdbaf9 Mon Sep 17 00:00:00 2001
From: rick2600 <ricks2600@gmail.com>
Date: Tue, 5 Oct 2021 01:45:59 -0300
Subject: [PATCH] fix issue #825

---
 src/core/array.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/core/array.c b/src/core/array.c
index 0c9810c7..36d82833 100644
--- a/src/core/array.c
+++ b/src/core/array.c
@@ -241,6 +241,11 @@ JANET_CORE_FN(cfun_array_concat,
                 int32_t j, len = 0;
                 const Janet *vals = NULL;
                 janet_indexed_view(argv[i], &vals, &len);
+                if (array->data == vals) {
+                    int32_t newcount = array->count + len;
+                    janet_array_ensure(array, newcount, 2);
+                    janet_indexed_view(argv[i], &vals, &len);
+                }
                 for (j = 0; j < len; j++)
                     janet_array_push(array, vals[j]);
             }