diff --git a/.gitignore b/.gitignore
index ab951f8..2f95cf9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,7 +6,7 @@ target/
 
 # Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
 # More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
-Cargo.lock
+# Cargo.lock
 
 # These are backup files generated by rustfmt
 **/*.rs.bk
diff --git a/day_01/Cargo.lock b/day_01/Cargo.lock
new file mode 100644
index 0000000..cdd8fbf
--- /dev/null
+++ b/day_01/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day_01"
+version = "0.1.0"
diff --git a/day_02/Cargo.lock b/day_02/Cargo.lock
new file mode 100644
index 0000000..9e264d4
--- /dev/null
+++ b/day_02/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day_02"
+version = "0.1.0"
diff --git a/day_03/Cargo.lock b/day_03/Cargo.lock
new file mode 100644
index 0000000..20e02e0
--- /dev/null
+++ b/day_03/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day_03"
+version = "0.1.0"
diff --git a/day_04/Cargo.lock b/day_04/Cargo.lock
new file mode 100644
index 0000000..0873af6
--- /dev/null
+++ b/day_04/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day_04"
+version = "0.1.0"