diff --git a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
index 1a0bbd9f50..0f2786a911 100644
--- a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
+++ b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
@@ -99,6 +99,7 @@ const LANGUAGE_MAP = {
   'text/x-vhdl': 'vhdl',
   'text/x-yaml': 'yaml',
   'text/vbscript': 'vbscript',
+  'application/x-mix-transfer': 'nix',
 };
 const ASYNC_DELAY = 10;