--- src/file.rs
+++ src/file.rs
@@ -442,9 +438,9 @@ mod tests {
             println!("Evaluating example file <{}>...", diff.to_str().unwrap());

             // Run highlighting on the file into a memory buffer
-            let mut actual_result: Vec<u8> = Vec::new();
-            highlight_diff(&mut fs::File::open(diff).unwrap(), &mut actual_result);
-            let actual_result = str::from_utf8(&actual_result).unwrap();
+            let file = tempfile::NamedTempFile::new().unwrap();
+            highlight_diff(&mut fs::File::open(diff).unwrap(), file.reopen().unwrap());
+            let actual_result = fs::read_to_string(file.path()).unwrap();

             // Load the corresponding .riff-output file into a string
             let basename = diff.file_stem().unwrap().to_str().unwrap();