diff --git a/src/formatters/custom.rs b/src/formatters/custom.rs
index baa51ae..115438b 100644
--- a/src/formatters/custom.rs
+++ b/src/formatters/custom.rs
@@ -80,8 +80,8 @@ where
     let mut stderr = child.stderr.take().expect("Failed to take stdout");
 
     let mut wtr = Writer::from_writer(stdin);
-    let mut captured_out = Vec::new();
-    let mut captured_err = Vec::new();
+    let mut captured_out = String::new();
+    let mut captured_err = String::new();
 
     for entry in entries {
         // write to process' stdin
@@ -92,14 +92,15 @@ where
             entry.note.unwrap_or_else(|| "".into()),
             entry.sheet,
         ])?;
+        wtr.flush()?;
 
         // read process' stdout and stderr
-        stdout.read_to_end(&mut captured_out)?;
-        write!(out, "{}", String::from_utf8_lossy(&captured_out))?;
+        stdout.read_to_string(&mut captured_out)?;
+        write!(out, "{}", &captured_out)?;
         captured_out.clear();
 
-        stderr.read_to_end(&mut captured_err)?;
-        write!(err, "{}", String::from_utf8_lossy(&captured_err))?;
+        stderr.read_to_string(&mut captured_err)?;
+        write!(err, "{}", &captured_err)?;
         captured_err.clear();
     }