diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go
index eda04ae47cc..dd7762ea92d 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go
@@ -807,6 +807,18 @@ func ValidateCustomResourceDefinitionOpenAPISchema(schema *apiextensions.JSONSch
 		} else {
 			allErrs = append(allErrs, field.Invalid(fldPath.Child("type"), schema.Type, "must be array if x-kubernetes-list-type is specified"))
 		}
+	} else if schema.XListType != nil && *schema.XListType == "set" && schema.Items != nil && schema.Items.Schema != nil { // by structural schema items are present
+		is := schema.Items.Schema
+		switch is.Type {
+		case "array":
+			if is.XListType != nil && *is.XListType != "atomic" { // atomic is the implicit default behaviour if unset, hence != atomic is wrong
+				allErrs = append(allErrs, field.Invalid(fldPath.Child("items").Child("x-kubernetes-list-type"), is.XListType, "must be atomic as item of a list with x-kubernetes-list-type=set"))
+			}
+		case "object":
+			if is.XMapType == nil || *is.XMapType != "atomic" { // granular is the implicit default behaviour if unset, hence nil and != atomic are wrong
+				allErrs = append(allErrs, field.Invalid(fldPath.Child("items").Child("x-kubernetes-map-type"), is.XListType, "must be atomic as item of a list with x-kubernetes-list-type=set"))
+			}
+		}
 	}
 
 	if schema.XListType != nil && *schema.XListType != "atomic" && *schema.XListType != "set" && *schema.XListType != "map" {
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation_test.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation_test.go
index 3359213bfc2..0266d799bc0 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation_test.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation_test.go
@@ -6300,6 +6300,170 @@ func TestValidateCustomResourceDefinitionValidation(t *testing.T) {
 			},
 			wantError: false,
 		},
+		{
+			name: "allowed list-type atomic",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("atomic"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type: "string",
+						},
+					},
+				},
+			},
+			wantError: false,
+		},
+		{
+			name: "allowed list-type atomic with non-atomic items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("atomic"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type:       "object",
+							Properties: map[string]apiextensions.JSONSchemaProps{},
+						},
+					},
+				},
+			},
+			wantError: false,
+		},
+		{
+			name: "allowed list-type set with scalar items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("set"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type: "string",
+						},
+					},
+				},
+			},
+			wantError: false,
+		},
+		{
+			name: "allowed list-type set with atomic map items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("set"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type:     "object",
+							XMapType: strPtr("atomic"),
+							Properties: map[string]apiextensions.JSONSchemaProps{
+								"foo": {Type: "string"},
+							},
+						},
+					},
+				},
+			},
+			wantError: false,
+		},
+		{
+			name: "invalid list-type set with non-atomic map items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("set"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type:     "object",
+							XMapType: strPtr("granular"),
+							Properties: map[string]apiextensions.JSONSchemaProps{
+								"foo": {Type: "string"},
+							},
+						},
+					},
+				},
+			},
+			wantError: true,
+		},
+		{
+			name: "invalid list-type set with unspecified map-type for map items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("set"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type: "object",
+							Properties: map[string]apiextensions.JSONSchemaProps{
+								"foo": {Type: "string"},
+							},
+						},
+					},
+				},
+			},
+			wantError: true,
+		},
+		{
+			name: "allowed list-type set with atomic list items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("set"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type:      "array",
+							XListType: strPtr("atomic"),
+							Items: &apiextensions.JSONSchemaPropsOrArray{
+								Schema: &apiextensions.JSONSchemaProps{
+									Type: "string",
+								},
+							},
+						},
+					},
+				},
+			},
+			wantError: false,
+		},
+		{
+			name: "allowed list-type set with unspecified list-type in list items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("set"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type: "array",
+							Items: &apiextensions.JSONSchemaPropsOrArray{
+								Schema: &apiextensions.JSONSchemaProps{
+									Type: "string",
+								},
+							},
+						},
+					},
+				},
+			},
+			wantError: false,
+		},
+		{
+			name: "invalid list-type set with with non-atomic list items",
+			input: apiextensions.CustomResourceValidation{
+				OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+					Type:      "array",
+					XListType: strPtr("set"),
+					Items: &apiextensions.JSONSchemaPropsOrArray{
+						Schema: &apiextensions.JSONSchemaProps{
+							Type:      "array",
+							XListType: strPtr("set"),
+							Items: &apiextensions.JSONSchemaPropsOrArray{
+								Schema: &apiextensions.JSONSchemaProps{
+									Type: "string",
+								},
+							},
+						},
+					},
+				},
+			},
+			wantError: true,
+		},
 		{
 			name: "invalid type with map type extension (granular)",
 			input: apiextensions.CustomResourceValidation{