diff --git a/src/mock.rs b/src/mock.rs
index 13fd3c6..df11a55 100644
--- a/src/mock.rs
+++ b/src/mock.rs
@@ -1,7 +1,7 @@
 pub(crate) mod image {
     use crate::image::Image;
 
-    pub fn bg() -> Image {
+    pub fn _bg() -> Image {
         Image {
             name: "bg".to_string(),
             pixels: vec![
@@ -17,7 +17,7 @@ pub(crate) mod image {
         }
     }
 
-    pub fn block() -> Image {
+    pub fn _block() -> Image {
         Image {
             name: "block".to_string(),
             pixels: vec![
@@ -49,7 +49,7 @@ pub(crate) mod image {
         }
     }
 
-    pub fn cat() -> Image {
+    pub fn _cat() -> Image {
         Image {
             name: "cat".to_string(),
             pixels: vec![