diff --git a/doc/author_karpov.txt b/doc/author_karpov.txt
new file mode 100644
index 0000000000..ba87602be2
--- /dev/null
+++ b/doc/author_karpov.txt
@@ -0,0 +1 @@
+I place my contributions to t8code under the FreeBSD license. Anton Karpov <karpovantonme@gmail.com>
diff --git a/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_stash.c b/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_stash.c
index ca7571dd68..d251da7f5c 100644
--- a/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_stash.c
+++ b/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_stash.c
@@ -67,7 +67,7 @@ t8_stash_destroy (t8_stash_t *pstash)
   }
   sc_array_reset (&stash->attributes);
   T8_FREE (stash);
-  pstash = NULL;
+  *pstash = NULL;
 }
 
 void
diff --git a/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_trees.cxx b/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_trees.cxx
index 87f88d10b8..31bad3d5b8 100644
--- a/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_trees.cxx
+++ b/src/t8_cmesh/t8_cmesh_internal/t8_cmesh_trees.cxx
@@ -1292,5 +1292,5 @@ t8_cmesh_trees_destroy (t8_cmesh_trees_t *ptrees)
   sc_mempool_destroy (trees->global_local_mempool);
 
   T8_FREE (trees);
-  ptrees = nullptr;
+  *ptrees = nullptr;
 }