diff --git a/pkgs/by-name/ma/mattermost/tests.nix b/pkgs/by-name/ma/mattermost/tests.nix
index 0eaf1c8966a9..60cf915ad92f 100644
--- a/pkgs/by-name/ma/mattermost/tests.nix
+++ b/pkgs/by-name/ma/mattermost/tests.nix
@@ -146,6 +146,10 @@ mattermost.overrideAttrs (
       ++ optionals (!stdenv.hostPlatform.isx86_64) [
         # aarch64: invalid operating system or processor architecture
         "TestCanIUpgradeToE0"
+
+        # aarch64: thumbnail previews are nondeterministic
+        "TestUploadFiles/multipart_Happy_image_thumbnail"
+        "TestUploadFiles/simple_Happy_image_thumbnail"
       ];
 
     preCheck = ''