diff --git a/README.md b/README.md
index b0c1b4f..684fe5b 100644
--- a/README.md
+++ b/README.md
@@ -29,16 +29,11 @@ Or install it yourself as:
 
     $ gem install tfoutputs
 
-
-
-
 ## Pre-requistes
 
 Ruby >= 2.2.2
 Your terraform state file also needs to be generated by terraform > 0.7.0  there are currently no plans to support terraform < 0.7.0
 
-
-
 ## Usage
 
 Require the gem:
@@ -63,6 +58,33 @@ S3 backends also have the following optional parameters:
 
 **profile** - The AWS Credential profile to use.
 
+If you have not set profile in the parmaters, make sure your AWS enviroment variables are set:
+```ruby
+ENV["AWS_DEFAULT_REGION"]
+ENV["AWS_PROFILE"]
+ENV["AWS_SESSION_TOKEN"]
+ENV["AWS_ACCESS_KEY_ID"]
+ENV["AWS_SECRET_ACCESS_KEY"]
+```
+
+For example:
+```ruby
+sts = Aws::STS::Client.new(
+    access_key_id: access_key_id,
+    secret_access_key: secret_access_key
+)
+role_credentials = Aws::AssumeRoleCredentials.new(
+    client: sts,
+    role_arn: "arn:aws:iam::#{accountnum}:role/#{assumerole}",
+    role_session_name: awsusername
+)
+ENV["AWS_DEFAULT_REGION"] = 'eu-west-1'
+ENV["AWS_PROFILE"] = awsusername
+ENV["AWS_SESSION_TOKEN"] = role_credentials.credentials.session_token
+ENV["AWS_ACCESS_KEY_ID"] = role_credentials.credentials.access_key_id
+ENV["AWS_SECRET_ACCESS_KEY"] = role_credentials.credentials.secret_access_key
+```
+
 Setting up a file backend:
 ```ruby
 config = {:backend => 'file', :options => { :file_path => '/path/to/state/file/terraform.tfstate' } }
@@ -71,7 +93,6 @@ puts(state_reader.my_output_name)
 
 ```
 
-
 Using multiple states with multiple backends:
 
 ```ruby