diff --git a/src/lib.rs b/src/lib.rs
index 3adfc3b..27e452c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -168,20 +168,20 @@ impl Level {
     }
 
     fn read_rle(map: &str) -> std::result::Result<Self, ReadError> {
-        let mut n: usize = 1;
-
         Self::read(
             map.chars()
-                .filter_map(|c| match c {
-                    '0'..='9' => {
-                        n = c.to_digit(10).unwrap() as usize;
-                        None
-                    }
-                    '|' => Some("\n".into()),
-                    _ => Some(c.to_string().repeat(n)),
+                .scan(1, |n, c| {
+                    Some(match c {
+                        '0'..='9' => {
+                            *n = c.to_digit(10).unwrap() as usize;
+                            None
+                        }
+                        '|' => Some("\n".to_string()),
+                        _ => Some(c.to_string().repeat(*n)),
+                    })
                 })
-                .collect::<Vec<String>>()
-                .join("")
+                .flatten()
+                .collect::<String>()
                 .as_bytes(),
         )
     }