diff --git a/README.md b/README.md
index a5010f8..f102789 100644
--- a/README.md
+++ b/README.md
@@ -50,7 +50,7 @@ pip install dt-cli
    1. Generate developer key and certificate from the CA
 
       ```shell
-      $ dt ext generate-developer-pem --ca-crt ca.crt --ca-key ca.key -o dev.pem
+      $ dt ext generate-developer-pem --ca-crt ca.pem --ca-key ca.key -o dev.pem
       Name: Ext
       Loading CA private key ca.key
       Loading CA certificate ca.pem
diff --git a/dtcli/scripts/dt.py b/dtcli/scripts/dt.py
index 4a63611..7304213 100644
--- a/dtcli/scripts/dt.py
+++ b/dtcli/scripts/dt.py
@@ -194,7 +194,7 @@ def extension():
            b) Generate developer key and certificate from the CA
 
            $ dt ext genca
-           $ dt ext generate-developer-pem --ca-crt ca.crt --ca-key ca.key -o dev.pem
+           $ dt ext generate-developer-pem --ca-crt ca.pem --ca-key ca.key -o dev.pem
 
         2. Build and sign the extension