diff --git a/go.mod b/go.mod
index d51b72d..3f3bdf5 100644
--- a/go.mod
+++ b/go.mod
@@ -8,7 +8,7 @@ require (
 	github.com/jordan-wright/email v4.0.1-0.20210109023952-943e75fe5223+incompatible
 	github.com/labstack/echo/v4 v4.15.1
 	github.com/labstack/gommon v0.4.2
-	github.com/slack-go/slack v0.18.0
+	github.com/slack-go/slack v0.21.1
 	gopkg.in/yaml.v2 v2.4.0
 )
 
diff --git a/go.sum b/go.sum
index 0273f12..aef81d5 100644
--- a/go.sum
+++ b/go.sum
@@ -26,8 +26,8 @@ github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWE
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/slack-go/slack v0.18.0 h1:PM3IWgAoaPTnitOyfy8Unq/rk8OZLAxlBUhNLv8sbyg=
-github.com/slack-go/slack v0.18.0/go.mod h1:K81UmCivcYd/5Jmz8vLBfuyoZ3B4rQC2GHVXHteXiAE=
+github.com/slack-go/slack v0.21.1 h1:vBHR+IkaXbv9RLY6w/RiN82D+5/OTI06CGqrlZ3Vyas=
+github.com/slack-go/slack v0.21.1/go.mod h1:K81UmCivcYd/5Jmz8vLBfuyoZ3B4rQC2GHVXHteXiAE=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=