diff --git a/src/AnnotationCreation.js b/src/AnnotationCreation.js
index f5e5995..8a338e0 100644
--- a/src/AnnotationCreation.js
+++ b/src/AnnotationCreation.js
@@ -449,7 +449,11 @@ AnnotationCreation.propTypes = {
   config: PropTypes.shape({
     annotation: PropTypes.shape({
       adapter: PropTypes.func,
-      defaults: PropTypes.objectOf(PropTypes.string),
+      defaults: PropTypes.objectOf(
+        PropTypes.oneOfType(
+          [PropTypes.bool, PropTypes.func, PropTypes.number, PropTypes.string]
+        )
+      ),
     }),
   }).isRequired,
   id: PropTypes.string.isRequired,