diff --git a/check.go b/check.go
index f6185e4..e1ceb76 100644
--- a/check.go
+++ b/check.go
@@ -4,7 +4,7 @@ import "context"
 
 type CheckPermissionRequest struct {
 	UserID string
-	Permission string
+	Permission IAMPermission
 }
 
 type CheckPermissionResponse struct {
@@ -15,7 +15,7 @@ func (c *PalAuthIAMClient) CheckPermission(ctx context.Context, request *CheckPe
 	resp := CheckPermissionResponse{}
 	err := c.getRequest(ctx, "/check", map[string]string{
 		"userId": request.UserID,
-		"permission": request.Permission,
+		"permission": string(request.Permission),
 	}, &resp)
 
 	if err != nil {