diff --git a/README.md b/README.md
index 099c573..f1663c9 100644
--- a/README.md
+++ b/README.md
@@ -52,24 +52,29 @@ resource "aws_sns_topic_subscription" "lambda_sns_to_slack" {
 }
 ```
 
-### Configurable variables
-
-|       **Variable**         |                          **Description**                          | **Required** | **Default**                    |
-|:--------------------------:|:-----------------------------------------------------------------:|--------------|--------------------------------|
-| **slack_webhook_url**      | Slack incoming webhook URL without protocol name.                 | yes          |                                |
-| **slack_channel_map**      | Topic-to-channel mapping.                                         | yes          |                                |
-| **lambda_function_name**   | AWS Lambda function name for the Slack notifier                   | no           | `"sns-to-slack"`               |
-| **default_username**       | Default username for notifications used if no matching one found. | no           |  `"AWS Lambda"`                |
-| **default_channel**        | Default channel used if no matching channel found.                | no           | `"#webhook-tests"`             |
-| **default_emoji**          | Default emoji used if no matching emoji found.                    | no           | `":information_source:"`       |
-| **lambda_iam_role_name**   | IAM role name for lambda functions.                               | no           | `"lambda-sns-to-slack"`        |
-| **lambda_iam_policy_name** | IAM policy name for lambda functions.                             | no           | `"lambda-sns-to-slack-policy"` |
-
-### Output variables
-
-| **Variable**            | **Description**                   |
-|-------------------------|-----------------------------------|
-| **lambda_function_arn** | AWS Lambda notifier function ARN. |
+## Configurable variables
+
+### Inputs
+
+| Name | Description | Type | Default | Required |
+|------|-------------|:----:|:-----:|:-----:|
+| default\_channel | Default channel used if no matching channel found | string | `#webhook-tests` | no |
+| default\_emoji | Default emoji used if no matching emoji found | string | `:information_source:` | no |
+| default\_username | Default username for notifications used if no matching one found | string | `AWS Lambda` | no |
+| lambda\_function\_name | AWS Lambda function name for the Slack notifier | string | `sns-to-slack` | no |
+| lambda\_iam\_policy\_name | IAM policy name for lambda functions | string | `lambda-sns-to-slack-policy` | no |
+| lambda\_iam\_role\_name | IAM role name for lambda functions | string | `lambda-sns-to-slack` | no |
+| slack\_channel\_map | Topic-to-channel mapping | map | - | yes |
+| slack\_webhook\_url | Slack incoming webhook URL without protocol name | string | - | yes |
+| username\_prefix | if sepecified the usernames that are looked up will be prefixed by this. Useful in situations where multiple accounts report to a single slack channel. | string | `` | no |
+
+### Outputs
+
+| Name | Description |
+|------|-------------|
+| lambda\_function\_arn | AWS Lambda notifier function ARN |
+
+
 
 ## Examples
 
diff --git a/build-function.sh b/build-function.sh
index 2de68e7..dc70899 100755
--- a/build-function.sh
+++ b/build-function.sh
@@ -16,6 +16,8 @@ pipenv run pip install -r <(pipenv lock -r) --target _build/
 cp lambda_function.py _build/
 
 pushd _build
+find . -name '*.pyc' -delete
+rm -f ${zipname}
 zip -r ${zipname} *
 cp ${zipname} ${outdir}
 popd
diff --git a/module/lambda.tf b/module/lambda.tf
index 5a051c3..fc782e6 100644
--- a/module/lambda.tf
+++ b/module/lambda.tf
@@ -17,6 +17,7 @@ resource "aws_lambda_function" "sns_to_slack" {
       DEFAULT_USERNAME = "${var.default_username}"
       DEFAULT_CHANNEL  = "${var.default_channel}"
       DEFAULT_EMOJI    = "${var.default_emoji}"
+      USERNAME_PREFIX  = "${var.username_prefix}"
     }
   }
 }
diff --git a/module/lambda/sns-to-slack.zip b/module/lambda/sns-to-slack.zip
index 154b633..cfd215d 100644
Binary files a/module/lambda/sns-to-slack.zip and b/module/lambda/sns-to-slack.zip differ
diff --git a/module/outputs.tf b/module/outputs.tf
index 15fe2e5..7682dc4 100644
--- a/module/outputs.tf
+++ b/module/outputs.tf
@@ -1,3 +1,4 @@
 output "lambda_function_arn" {
-  value = "${aws_lambda_function.sns_to_slack.arn}"
+  value       = "${aws_lambda_function.sns_to_slack.arn}"
+  description = "AWS Lambda notifier function ARN"
 }
diff --git a/module/variables.tf b/module/variables.tf
index 82e95f5..fb9af89 100644
--- a/module/variables.tf
+++ b/module/variables.tf
@@ -1,37 +1,51 @@
 variable "slack_webhook_url" {
-  type = "string"
+  type        = "string"
+  description = "Slack incoming webhook URL without protocol name"
 }
 
 variable "slack_channel_map" {
-  type = "map"
+  type        = "map"
+  description = "Topic-to-channel mapping"
 }
 
 variable "lambda_function_name" {
-  type    = "string"
-  default = "sns-to-slack"
+  type        = "string"
+  default     = "sns-to-slack"
+  description = "AWS Lambda function name for the Slack notifier"
 }
 
 variable "default_username" {
-  type    = "string"
-  default = "AWS Lambda"
+  type        = "string"
+  default     = "AWS Lambda"
+  description = "Default username for notifications used if no matching one found"
+}
+
+variable "username_prefix" {
+  type        = "string"
+  default     = ""
+  description = "if sepecified the usernames that are looked up will be prefixed by this. Useful in situations where multiple accounts report to a single slack channel."
 }
 
 variable "default_channel" {
-  type    = "string"
-  default = "#webhook-tests"
+  type        = "string"
+  default     = "#webhook-tests"
+  description = "Default channel used if no matching channel found"
 }
 
 variable "default_emoji" {
-  type    = "string"
-  default = ":information_source:"
+  type        = "string"
+  default     = ":information_source:"
+  description = "Default emoji used if no matching emoji found"
 }
 
 variable "lambda_iam_role_name" {
-  type    = "string"
-  default = "lambda-sns-to-slack"
+  type        = "string"
+  default     = "lambda-sns-to-slack"
+  description = "IAM role name for lambda functions"
 }
 
 variable "lambda_iam_policy_name" {
-  type    = "string"
-  default = "lambda-sns-to-slack-policy"
+  type        = "string"
+  default     = "lambda-sns-to-slack-policy"
+  description = "IAM policy name for lambda functions"
 }
diff --git a/sns-to-slack/lambda_function.py b/sns-to-slack/lambda_function.py
index 0b359ec..7baed46 100644
--- a/sns-to-slack/lambda_function.py
+++ b/sns-to-slack/lambda_function.py
@@ -46,6 +46,7 @@
 DEFAULT_USERNAME = os.environ.get('DEFAULT_USERNAME', 'AWS Lambda')
 DEFAULT_CHANNEL = os.environ.get('DEFAULT_CHANNEL', '#webhook-tests')
 DEFAULT_EMOJI = os.environ.get('DEFAULT_EMOJI', ':information_source:')
+USERNAME_PREFIX = os.environ.get('USERNAME_PREFIX', '')
 
 
 def get_slack_emoji(event_src, topic_name, event_cond='default'):
@@ -92,7 +93,7 @@ def get_slack_username(event_src):
         'rds': 'AWS RDS'}
 
     try:
-        return username_map[event_src]
+        return "{0}{1}".format(USERNAME_PREFIX, username_map[event_src])
     except KeyError:
         return DEFAULT_USERNAME