diff --git a/greetd_ipc/src/lib.rs b/greetd_ipc/src/lib.rs
index 970e6e8..c20c00f 100644
--- a/greetd_ipc/src/lib.rs
+++ b/greetd_ipc/src/lib.rs
@@ -75,7 +75,11 @@ pub enum Request {
 
     /// Start a successfully logged in session. This will fail if the session
     /// has pending messages or has encountered an error.
-    StartSession { cmd: Vec<String>, env: Vec<String> },
+    StartSession {
+        cmd: Vec<String>,
+        #[serde(default)]
+        env: Vec<String>,
+    },
 
     /// Cancel a session. This can only be done if the session has not been
     /// started. Cancel does not have to be called if an error has been