diff --git a/README.md b/README.md
index 8bc77e0..7b9f769 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ Kubernetes The Hard Way is optimized for learning, which means taking the long r
 
 ## Overview of the Network Architecture
 
-![architecture network](docs/images/architecture-network.PNG)
+![architecture network](docs/images/architecture-network.png)
 
 ## Copyright
 
diff --git a/docs/01-prerequisites.md b/docs/01-prerequisites.md
index 8bb60d9..53a94d0 100644
--- a/docs/01-prerequisites.md
+++ b/docs/01-prerequisites.md
@@ -47,7 +47,7 @@ The reverse proxy / client tools / gateway VM need to have 2 network interfaces,
 
 This diagram represents the network design:
 
-![architecture network](images/architecture-network.PNG)
+![architecture network](images/architecture-network.png)
 
 > If you want, you can define the IPv6 stack configuration.