diff --git a/src/file/env.rs b/src/file/env.rs
index 5635b67..2cdc30d 100644
--- a/src/file/env.rs
+++ b/src/file/env.rs
@@ -1,9 +1,11 @@
+use crate::prelude::*;
+
 use std::fs::{File, OpenOptions};
 use std::io::Write;
 
-pub type FileOpenFn = Box<dyn Fn(&str) -> std::io::Result<File>>;
+pub type FileOpenFn = Box<dyn Fn(&str) -> Result<File>>;
 
-pub type FileAppendLineFn = Box<dyn Fn(&str, &str) -> std::io::Result<()>>;
+pub type FileAppendLineFn = Box<dyn Fn(&str, &str) -> Result<()>>;
 
 pub struct FileEnv {
     pub open: FileOpenFn,
@@ -12,7 +14,7 @@ pub struct FileEnv {
 impl Default for FileEnv {
     fn default() -> Self {
         Self {
-            open: Box::new(|path| File::open(path)),
+            open: Box::new(|path| Ok(File::open(path)?)),
             append_line: Box::new(|file_name, line| {
                 let mut file = OpenOptions::new()
                     .write(true)
diff --git a/src/file/mod.rs b/src/file/mod.rs
index 3a55a73..6b6c968 100644
--- a/src/file/mod.rs
+++ b/src/file/mod.rs
@@ -1,4 +1,6 @@
 mod env;
 pub mod read;
 
+pub use env::FileAppendLineFn;
 pub use env::FileEnv;
+pub use env::FileOpenFn;