diff --git a/README.md b/README.md
index d28bd06..6fbbcf5 100644
--- a/README.md
+++ b/README.md
@@ -62,9 +62,9 @@ config :ex_aws,
   awscli_auth_adapter: ExAws.STS.AuthCache.AssumeRoleCredentialsAdapter,
   awscli_credentials: %{
     "default" => %{
-      role_arn: {:system, "AWS_ROLE_ARN"},
-      access_key_id: {:system, "AWS_ACCESS_KEY_ID"},
-      secret_access_key: {:system, "AWS_SECRET_ACCESS_KEY"},
+      role_arn: System.get_env("AWS_ROLE_ARN"),
+      access_key_id: System.get_env("AWS_ACCESS_KEY_ID"),
+      secret_access_key: System.get_env("AWS_SECRET_ACCESS_KEY"),
       source_profile: "default"
     }
   }
@@ -81,7 +81,13 @@ Similarly, it is possible to use a web identity token to perform the assume role
 config :ex_aws,
   secret_access_key: [{:awscli, "profile_name", 30}],
   access_key_id: [{:awscli, "profile_name", 30}],
-  awscli_auth_adapter: ExAws.STS.AuthCache.AssumeRoleWebIdentityAdapter
+  awscli_auth_adapter: ExAws.STS.AuthCache.AssumeRoleWebIdentityAdapter,
+  awscli_credentials: %{
+    "profile_name" => %{
+      role_arn: System.get_env("AWS_ROLE_ARN"),
+      source_profile: "profile_name"
+    }
+  }
 ```
 
 ## License