diff --git a/packages/diffs/src/utils/parseDiffFromFile.ts b/packages/diffs/src/utils/parseDiffFromFile.ts
index 6d7a1948c..dd5dc8f57 100644
--- a/packages/diffs/src/utils/parseDiffFromFile.ts
+++ b/packages/diffs/src/utils/parseDiffFromFile.ts
@@ -43,5 +43,10 @@ export function parseDiffFromFile(
       'parseDiffFrom: FileInvalid diff -- probably need to fix something -- if the files are the same maybe?'
     );
   }
+  // If we've been provided an override for language in the newFile, let’s pass
+  // it through to FileDiffMetadata.
+  if (newFile.lang != null) {
+    fileData.lang = newFile.lang;
+  }
   return fileData;
 }