diff --git a/go.mod b/go.mod
index 5338d85..f83eb98 100644
--- a/go.mod
+++ b/go.mod
@@ -1,7 +1,7 @@
 module github.com/mackerelio/mackerel-client-go
 
-go 1.18
+go 1.21.0
 
 require github.com/kylelemons/godebug v1.1.0
 
-retract v0.33.0 // API endpoint for DeleteGraphDef has changed.
\ No newline at end of file
+retract v0.33.0 // API endpoint for DeleteGraphDef has changed.