diff --git a/src/main.rs b/src/main.rs
index 74abb8f..8338576 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,7 +2,7 @@ use core::str;
 use std::{
     fmt::Display,
     fs::File,
-    io::{BufRead, BufReader},
+    io::{self, BufRead, BufReader},
     path::{self, PathBuf},
     str::FromStr,
 };
@@ -369,14 +369,7 @@ fn main() -> Result<()> {
             debug!("{:?}", result);
 
             // Print boards to retest
-            for (pos, boardresult) in &result.board_results {
-                if let Some(reason) = boardresult.is_need_retest() {
-                    println!(
-                        "Board {} at {} need retest for {}",
-                        boardresult.id.id, pos, reason
-                    );
-                }
-            }
+            result.print_boards_to_retest(io::stdout())?;
 
             let outfile = outfile.unwrap_or(get_output_filename(&result));
 
diff --git a/src/masterlog.rs b/src/masterlog.rs
index 8052778..6db76d8 100644
--- a/src/masterlog.rs
+++ b/src/masterlog.rs
@@ -1,4 +1,9 @@
-use std::{collections::BTreeMap, io::BufRead, path::PathBuf, str::FromStr};
+use std::{
+    collections::BTreeMap,
+    io::{BufRead, Write},
+    path::PathBuf,
+    str::FromStr,
+};
 
 use anyhow::{anyhow, Context, Result};
 use chrono::{DateTime, Utc};
@@ -301,6 +306,19 @@ impl MasterLogResult {
             filename,
         })
     }
+
+    pub fn print_boards_to_retest(&self, mut wtr: impl Write) -> Result<()> {
+        for (pos, boardresult) in &self.board_results {
+            if let Some(reason) = boardresult.is_need_retest() {
+                writeln!(
+                    wtr,
+                    "Board {} at {} need retest for {}",
+                    boardresult.id.id, pos, reason
+                )?;
+            }
+        }
+        Ok(())
+    }
 }
 
 pub fn get_output_filename(result: &MasterLogResult) -> PathBuf {