diff --git a/pkg/models/kanban.go b/pkg/models/kanban.go
index d9dbd6efa3f..ad2d8bb291e 100644
--- a/pkg/models/kanban.go
+++ b/pkg/models/kanban.go
@@ -37,7 +37,7 @@ type Bucket struct {
 	Tasks []*Task `xorm:"-" json:"tasks"`
 
 	// How many tasks can be at the same time on this board max
-	Limit int64 `xorm:"default 0" json:"limit"`
+	Limit int64 `xorm:"default 0" json:"limit" minimum:"0" valid:"range(0|9223372036854775807)"`
 	// If this bucket is the "done bucket". All tasks moved into this bucket will automatically marked as done. All tasks marked as done from elsewhere will be moved into this bucket.
 	IsDoneBucket bool `xorm:"BOOL" json:"is_done_bucket"`
 
diff --git a/pkg/swagger/docs.go b/pkg/swagger/docs.go
index 81c5871b0cf..64750035785 100644
--- a/pkg/swagger/docs.go
+++ b/pkg/swagger/docs.go
@@ -7204,7 +7204,8 @@ var doc = `{
                 },
                 "limit": {
                     "description": "How many tasks can be at the same time on this board max",
-                    "type": "integer"
+                    "type": "integer",
+                    "minimum": 0
                 },
                 "list_id": {
                     "description": "The list this bucket belongs to.",
diff --git a/pkg/swagger/swagger.json b/pkg/swagger/swagger.json
index 45bc56c7a08..90e4a2bac69 100644
--- a/pkg/swagger/swagger.json
+++ b/pkg/swagger/swagger.json
@@ -7187,7 +7187,8 @@
                 },
                 "limit": {
                     "description": "How many tasks can be at the same time on this board max",
-                    "type": "integer"
+                    "type": "integer",
+                    "minimum": 0
                 },
                 "list_id": {
                     "description": "The list this bucket belongs to.",
diff --git a/pkg/swagger/swagger.yaml b/pkg/swagger/swagger.yaml
index 6d186120459..c52ad481fb7 100644
--- a/pkg/swagger/swagger.yaml
+++ b/pkg/swagger/swagger.yaml
@@ -91,6 +91,7 @@ definitions:
         type: boolean
       limit:
         description: How many tasks can be at the same time on this board max
+        minimum: 0
         type: integer
       list_id:
         description: The list this bucket belongs to.