diff --git a/.devcontainer/.env b/.devcontainer/.env
new file mode 100644
index 000000000..91c93d91d
--- /dev/null
+++ b/.devcontainer/.env
@@ -0,0 +1 @@
+MAS_OAUTH2_ISSUER="https://${CODESPACE_NAME}-8080.githubpreview.dev/"
\ No newline at end of file
diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
index 141cb39ae..421130224 100644
--- a/.devcontainer/Dockerfile
+++ b/.devcontainer/Dockerfile
@@ -3,6 +3,8 @@ FROM mcr.microsoft.com/vscode/devcontainers/rust:0-1
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
      && apt-get -y install --no-install-recommends postgresql-client
 
+COPY .env /.env
+
 # TODO: pre-build custom images, those take too much time
 #RUN cargo install sqlx-cli --no-default-features --features postgres
 #RUN cargo install cargo-edit
\ No newline at end of file
diff --git a/Cargo.lock b/Cargo.lock
index 1aaa2d9d7..245c68a2b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1255,6 +1255,7 @@ dependencies = [
  "cookie",
  "crc 2.0.0",
  "data-encoding",
+ "dotenv",
  "figment",
  "headers",
  "hyper",
diff --git a/matrix-authentication-service/Cargo.toml b/matrix-authentication-service/Cargo.toml
index cdec109e5..a9c9a4f5e 100644
--- a/matrix-authentication-service/Cargo.toml
+++ b/matrix-authentication-service/Cargo.toml
@@ -39,6 +39,7 @@ serde_with = { version = "1.9.4", features = ["hex", "chrono"] }
 clap = "3.0.0-beta.2"
 figment = { version = "0.10.6", features = ["env", "yaml", "test"] }
 schemars = { version = "0.8.3", features = ["url", "chrono"] }
+dotenv = "0.15.0"
 
 # Password hashing
 argon2 = { version = "0.2.2", features = ["password-hash"] }
diff --git a/matrix-authentication-service/src/main.rs b/matrix-authentication-service/src/main.rs
index f3adcadc6..068ccc598 100644
--- a/matrix-authentication-service/src/main.rs
+++ b/matrix-authentication-service/src/main.rs
@@ -34,6 +34,9 @@ use self::cli::RootCommand;
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
+    // Load environment variables from .env files
+    dotenv::dotenv()?;
+
     // Setup logging & tracing
     let fmt_layer = tracing_subscriber::fmt::layer();
     let filter_layer = EnvFilter::try_from_default_env().or_else(|_| EnvFilter::try_new("info"))?;