diff --git a/pkg/apis/scheduling/types.go b/pkg/apis/scheduling/types.go
index 5130d624a03..1e81eb66190 100644
--- a/pkg/apis/scheduling/types.go
+++ b/pkg/apis/scheduling/types.go
@@ -44,8 +44,11 @@ type PriorityClass struct {
 	// receive when they have the name of this class in their pod spec.
 	Value int32
 
-	// GlobalDefault specifies whether this PriorityClass should be considered as
+	// globalDefault specifies whether this PriorityClass should be considered as
 	// the default priority for pods that do not have any priority class.
+	// Only one PriorityClass with can be marked as `globalDefault`. Due to race conditions, more than
+	// one PriorityClasses might be created with their `globalDefault` field set to true. In that case,
+	// the smallest value of such global default PriorityClasses will be used as the default priority.
 	// +optional
 	GlobalDefault bool
 
diff --git a/staging/src/k8s.io/api/scheduling/v1alpha1/types.go b/staging/src/k8s.io/api/scheduling/v1alpha1/types.go
index 07bf337fb14..bba67b4df5d 100644
--- a/staging/src/k8s.io/api/scheduling/v1alpha1/types.go
+++ b/staging/src/k8s.io/api/scheduling/v1alpha1/types.go
@@ -39,6 +39,9 @@ type PriorityClass struct {
 
 	// globalDefault specifies whether this PriorityClass should be considered as
 	// the default priority for pods that do not have any priority class.
+	// Only one PriorityClass with can be marked as `globalDefault`. Due to race conditions, more than
+	// one PriorityClasses might be created with their `globalDefault` field set to true. In that case,
+	// the smallest value of such global default PriorityClasses will be used as the default priority.
 	// +optional
 	GlobalDefault bool `json:"globalDefault,omitempty" protobuf:"bytes,3,opt,name=globalDefault"`