diff --git a/core-principles/minimal-api-surface.md b/core-principles/minimal-api-surface.md
index e65ce9c..7c39b01 100644
--- a/core-principles/minimal-api-surface.md
+++ b/core-principles/minimal-api-surface.md
@@ -1,2 +1,2 @@
 # Minimal API Surface
-Every API design MUST aim for a minimal API surface without sacrificing on product requirements. API design SHOULD NOT include unnecessary resources, relations, actions or data. API design SHOULD NOT add functionality until deemed necessary ([YAGNI principle](https://martinfowler.com/bliki/Yagni.html)).
\ No newline at end of file
+Every API design **MUST** aim for a minimal API surface without sacrificing on product requirements. API design **SHOULD NOT** include unnecessary resources, relations, actions or data. API design **SHOULD NOT** add functionality until deemed necessary ([YAGNI principle](https://martinfowler.com/bliki/Yagni.html)).
\ No newline at end of file
diff --git a/core-principles/rules-for-extending.md b/core-principles/rules-for-extending.md
index 5f0de5b..b3551ee 100644
--- a/core-principles/rules-for-extending.md
+++ b/core-principles/rules-for-extending.md
@@ -1,7 +1,7 @@
 # Rules for Extending
-Any modification to an existing API MUST avoid breaking changes and MUST maintain backward compatibility.
+Any modification to an existing API **MUST** avoid breaking changes and MUST maintain backward compatibility.
 
-In particular, any change to an API MUST follow the following Rules for Extending:
+In particular, any change to an API **MUST** follow the following **Rules for Extending**:
 
 1. **You MUST NOT take anything away** (related: [Minimal Surface Principle](core-principles/minimal-api-surface.md)
 , [Robustness Principle](core-principles/robustness.md))