diff --git a/day-1/go.mod b/day-1/go.mod
index 9eb1bf5..369af8e 100644
--- a/day-1/go.mod
+++ b/day-1/go.mod
@@ -1,6 +1,6 @@
 module github.com/onyx-and-iris/aoc2023/day-1
 
-go 1.20
+go 1.21.5
 
 require github.com/stretchr/testify v1.8.4
 
diff --git a/day-2/go.mod b/day-2/go.mod
index bcb3f01..657578a 100644
--- a/day-2/go.mod
+++ b/day-2/go.mod
@@ -1,3 +1,3 @@
 module github.com/onyx-and-iris/aoc2023/day-2
 
-go 1.20
+go 1.21.5
diff --git a/day-3/go.mod b/day-3/go.mod
index 0604fa0..85d7f16 100644
--- a/day-3/go.mod
+++ b/day-3/go.mod
@@ -1,5 +1,5 @@
 module github.com/onyx-and-iris/aoc2023/day-3
 
-go 1.20
+go 1.21.5
 
 require github.com/go-playground/assert/v2 v2.2.0
diff --git a/day-4/go.mod b/day-4/go.mod
index 78166bc..402304a 100644
--- a/day-4/go.mod
+++ b/day-4/go.mod
@@ -1,5 +1,5 @@
 module github.com/onyx-and-iris/aoc2023/day-4
 
-go 1.20
+go 1.21.5
 
 require github.com/go-playground/assert v1.2.1
diff --git a/day-5/go.mod b/day-5/go.mod
index 1ee3b8e..d0bcd31 100644
--- a/day-5/go.mod
+++ b/day-5/go.mod
@@ -1,6 +1,6 @@
 module github.com/onyx-and-iris/aoc2023/day-5
 
-go 1.20
+go 1.21.5
 
 require github.com/sirupsen/logrus v1.9.3
 
diff --git a/day-6/go.mod b/day-6/go.mod
index 0127354..4689e35 100644
--- a/day-6/go.mod
+++ b/day-6/go.mod
@@ -1,3 +1,3 @@
 module github.com/onyx-and-iris/aoc2023/day-6
 
-go 1.20
+go 1.21.5
diff --git a/day-7/go.mod b/day-7/go.mod
index 5be8b24..496f8d6 100644
--- a/day-7/go.mod
+++ b/day-7/go.mod
@@ -1,6 +1,6 @@
 module github.com/onyx-and-iris/aoc2023/day-7
 
-go 1.20
+go 1.21.5
 
 require (
 	github.com/samber/lo v1.39.0 // indirect
diff --git a/day-8/go.mod b/day-8/go.mod
index e9a42c2..626347a 100644
--- a/day-8/go.mod
+++ b/day-8/go.mod
@@ -1,3 +1,3 @@
 module github.com/onyx-and-iris/aoc2023/day-8
 
-go 1.20
+go 1.21.5
diff --git a/day-9/go.mod b/day-9/go.mod
index 2ec3aca..9eccf16 100644
--- a/day-9/go.mod
+++ b/day-9/go.mod
@@ -1,3 +1,3 @@
 module github.com/onyx-and-iris/aoc2023/day-9
 
-go 1.20
+go 1.21.5