diff --git a/Cargo.lock b/Cargo.lock
index 7d3fc8f..0755741 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,185 +1,187 @@
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+# It is not intended for manual editing.
+version = 3
+
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- "libc 0.2.44 (registry+https://github.com/rust-lang/crates.io-index)",
- "version_check 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
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+ "libc",
+ "version_check",
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- "winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi-i686-pc-windows-gnu",
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 ]
 
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diff --git a/Cargo.toml b/Cargo.toml
index 798ef0a..1aefac3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 name = "aoc_2018"
 version = "0.1.0"
 authors = ["Johannes <jschaef@mail.uni-paderborn.de>"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 regex = "1.1.0"
diff --git a/src/tasks/day22.rs b/src/tasks/day22.rs
index e6a7a2f..eaf116d 100644
--- a/src/tasks/day22.rs
+++ b/src/tasks/day22.rs
@@ -154,7 +154,7 @@ impl Cave {
             (position.0 as i32, position.1 as i32 - 1),
             (position.0 as i32, position.1 as i32 + 1),
         ]
-        .into_iter()
+        .iter()
         .filter_map(|(x, y)| {
             if *x >= 0 && *y >= 0 {
                 Some(Node(*x as usize, *y as usize, position.2))