diff --git a/lib/aws_codegen/post_service.ex b/lib/aws_codegen/post_service.ex
index 55edf02..141b79d 100644
--- a/lib/aws_codegen/post_service.ex
+++ b/lib/aws_codegen/post_service.ex
@@ -111,7 +111,12 @@ defmodule AWS.CodeGen.PostService do
       signing_name: signing_name,
       signature_version: AWS.CodeGen.Util.get_signature_version(service),
       service_id: AWS.CodeGen.Util.get_service_id(service),
-      endpoint_url_env_var: "AWS_ENDPOINT_URL_" <> spec.module_name |> String.upcase(),
+      endpoint_url_env_var:
+        "AWS_ENDPOINT_URL_" <>
+          (service
+           |> AWS.CodeGen.Util.get_service_id()
+           |> String.replace(" ", "_")
+           |> String.upcase()),
       target_prefix: target_prefix(spec.api)
     }
   end
diff --git a/lib/aws_codegen/rest_service.ex b/lib/aws_codegen/rest_service.ex
index 500a237..719007b 100644
--- a/lib/aws_codegen/rest_service.ex
+++ b/lib/aws_codegen/rest_service.ex
@@ -157,7 +157,12 @@ defmodule AWS.CodeGen.RestService do
       signing_name: signing_name,
       signature_version: AWS.CodeGen.Util.get_signature_version(service),
       service_id: AWS.CodeGen.Util.get_service_id(service),
-      endpoint_url_env_var: "AWS_ENDPOINT_URL_" <> spec.module_name |> String.upcase(),
+      endpoint_url_env_var:
+        "AWS_ENDPOINT_URL_" <>
+          (service
+           |> AWS.CodeGen.Util.get_service_id()
+           |> String.replace(" ", "_")
+           |> String.upcase()),
       ## TODO: metadata["targetPrefix"],
       target_prefix: nil,
       shapes: Shapes.collect_shapes(language, spec.api)
diff --git a/test/aws_codegen/rest_service_test.exs b/test/aws_codegen/rest_service_test.exs
index 623a0fb..e38a160 100644
--- a/test/aws_codegen/rest_service_test.exs
+++ b/test/aws_codegen/rest_service_test.exs
@@ -51,7 +51,7 @@ defmodule AWS.CodeGen.RestServiceTest do
                module_name: "AWS.CloudTrailData",
                protocol: "rest-json",
                service_id: "CloudTrail Data",
-               endpoint_url_env_var: "AWS_ENDPOINT_URL_AWS.CLOUDTRAILDATA", # For Erlang this would be: AWS_ENDPOINT_URL_CLOUDTRAILDATA
+               endpoint_url_env_var: "AWS_ENDPOINT_URL_CLOUDTRAIL_DATA",
                signature_version: "v4",
                signing_name: "cloudtrail-data",
                target_prefix: nil