diff --git a/README.md b/README.md
index 4e18cdb..28f1366 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ Public key infrastructure (PKI) related resources.
 
 ### Adding to Trust Stores
 #### Arch Linux
-`sudo trust anchor --store root.crt`
+`sudo trust anchor --store root.cer`
 
 #### Debian
 ```
@@ -19,15 +19,15 @@ sudo update-ca-certificates
 ```
 
 #### iOS
-Visit [https://pki.vimium.com/root.crt](https://pki.vimium.com/root.crt) in Safari.
+Visit [https://pki.vimium.com/root.cer](https://pki.vimium.com/root.cer) in Safari.
 1. Go to Settings > General > About > Certificate Trust Settings
 1. Turn on trust for "Vimium Root CA" under "Enable full trust for root certificates"
 
 #### macOS
-`sudo security add-trusted-cert -d -p ssl -p basic -k /Library/Keychains/System.keychain root.crt`
+`sudo security add-trusted-cert -d -p ssl -p basic -k /Library/Keychains/System.keychain root.cer`
 
 #### Windows
-`certutil -addstore root root.crt`
+`certutil -addstore root root.cer`
 
 ## Web
 Public documentation and files at [http://pki.vimium.com](http://pki.vimium.com).