diff --git a/CHANGELOG.md b/CHANGELOG.md
index e8245e1f..221a9120 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,9 +2,12 @@
 - Implement FHIR Resources with io-ts
 - You can now validate your json and strongly type data.  
 
+**known limitation**
+Currently an issue occurs with io-ts union that prevent the use caontained property of FHIR Resources. So for now there are deactivated.
+
 # 4.0.1
 - Fix: properties are now lowercase as FHIR spec 
 - Fix: Enum generation 
 
 # 4.0.0
-- Create model for FHIR R4 Resources 
\ No newline at end of file
+- Create model for FHIR R4 Resources