diff --git a/pkg/channel/list.go b/pkg/channel/list.go
index 7ce5c3a..95192b0 100644
--- a/pkg/channel/list.go
+++ b/pkg/channel/list.go
@@ -35,12 +35,13 @@ type ListGroupChannelRequest struct {
 	PublicMode string
 	// SuperMod&e specifies which type of group channels to retrieve. Acceptable
 	// values are the following:
-	// - all (default): All types of group channels including Supergroup channels
-	// are returned.
-	// - super: Only Supergroup channels are returned.
-	// - nonsuper: Group channels excluding Supergroup channels are returned.
+	// - SuperModeAll (default): All types of group channels including Supergroup
+	// channels are returned.
+	// - SuperModeSuper: Only Supergroup channels are returned.
+	// - SuperModeNonSuper: Group channels excluding Supergroup channels are
+	// returned.
 	// Optional.
-	SuperMode string
+	SuperMode SuperMode
 	// CreatedAfter restricts the search scope to only retrieve group channels
 	// which have been created after the specified time, in Unix milliseconds
 	// format.
@@ -255,7 +256,7 @@ func listChannelRequestToMap(lcr ListGroupChannelRequest) map[string]string {
 	}
 
 	if lcr.SuperMode != "" {
-		m["super_mode"] = lcr.SuperMode
+		m["super_mode"] = string(lcr.SuperMode)
 	}
 
 	if lcr.CreatedAfter != nil {
diff --git a/pkg/channel/types.go b/pkg/channel/types.go
index 857516c..bed9c6a 100644
--- a/pkg/channel/types.go
+++ b/pkg/channel/types.go
@@ -14,10 +14,12 @@ const (
 	PublicModeNonPublic string = "private"
 )
 
+type SuperMode string
+
 const (
-	SuperModeAll      string = "all"
-	SuperModeSuper    string = "super"
-	SuperModeNonSuper string = "nonsuper"
+	SuperModeAll      SuperMode = "all"
+	SuperModeSuper    SuperMode = "super"
+	SuperModeNonSuper SuperMode = "nonsuper"
 )
 
 const (
diff --git a/pkg/user/joined_channel.go b/pkg/user/joined_channel.go
index 3cea705..c7c5612 100644
--- a/pkg/user/joined_channel.go
+++ b/pkg/user/joined_channel.go
@@ -46,7 +46,7 @@ type GetGroupChannelCountRequest struct {
 	// SuperMode restricts the search scope to either Supergroup channels or
 	// non-Supergroup channels or both. Acceptable values are all, super, and
 	// nonsuper. If not specified, the default value is all.
-	SuperMode string `json:"super_mode,omitempty"`
+	SuperMode SuperMode `json:"super_mode,omitempty"`
 }
 
 type GetGroupChannelCountResponse struct {
diff --git a/pkg/user/types.go b/pkg/user/types.go
index 8f3cf97..a38a6f8 100644
--- a/pkg/user/types.go
+++ b/pkg/user/types.go
@@ -1,7 +1,9 @@
 package user
 
+type SuperMode string
+
 const (
-	SuperModeAll      string = "all"
-	SuperModeSuper    string = "super"
-	SuperModeNonSuper string = "nonsuper"
+	SuperModeAll      SuperMode = "all"
+	SuperModeSuper    SuperMode = "super"
+	SuperModeNonSuper SuperMode = "nonsuper"
 )
diff --git a/pkg/user/unread_messages.go b/pkg/user/unread_messages.go
index 470ac97..c6b3643 100644
--- a/pkg/user/unread_messages.go
+++ b/pkg/user/unread_messages.go
@@ -14,7 +14,7 @@ type GetUnreadMessagesCountRequest struct {
 	// SuperMode restricts the search scope to either Supergroup channels or
 	// non-Supergroup channels or both. Acceptable values are all, super, and
 	// nonsuper. If not specified, the default value is all.
-	SuperMode string `json:"super_mode,omitempty"`
+	SuperMode SuperMode `json:"super_mode,omitempty"`
 }
 
 type GetUnreadMessagesCountResponse struct {