diff --git a/source/JSONSchema-Core/JSONPrimitiveSchema.class.st b/source/JSONSchema-Core/JSONPrimitiveSchema.class.st
index e09b8c0..e77914c 100644
--- a/source/JSONSchema-Core/JSONPrimitiveSchema.class.st
+++ b/source/JSONSchema-Core/JSONPrimitiveSchema.class.st
@@ -84,6 +84,11 @@ JSONPrimitiveSchema >> nullable [
 	^ nullable ~~ false
 ]
 
+{ #category : 'accessing' }
+JSONPrimitiveSchema >> nullable: aBoolean [
+	nullable := aBoolean
+]
+
 { #category : 'reading' }
 JSONPrimitiveSchema >> read: anObject [
 	| value |