diff --git a/managed/resource_cluster.go b/managed/resource_cluster.go
index 6dfb313..3f52608 100644
--- a/managed/resource_cluster.go
+++ b/managed/resource_cluster.go
@@ -170,6 +170,7 @@ and modify the backup schedule of the cluster being created.`,
 						Description: "The time interval in minutes for the incremental backup schedule.",
 						Type:        types.Int64Type,
 						Optional:    true,
+						Validators:  []tfsdk.AttributeValidator{int64validator.AtLeast(1)},
 					},
 				}),
 			},