diff --git a/services/tunnelbroker/src/notifs/fcm/error.rs b/services/tunnelbroker/src/notifs/fcm/error.rs
index 4197782f9..69f5a5956 100644
--- a/services/tunnelbroker/src/notifs/fcm/error.rs
+++ b/services/tunnelbroker/src/notifs/fcm/error.rs
@@ -1,16 +1,18 @@
+use crate::notifs::fcm::response::FCMError;
 use derive_more::{Display, Error, From};
 
 #[derive(Debug, From, Display, Error)]
 pub enum Error {
   JWTError,
   ReqwestError(reqwest::Error),
   InvalidHeaderValue(reqwest::header::InvalidHeaderValue),
   SerdeJson(serde_json::Error),
   FCMTokenNotInitialized,
+  FCMError(FCMError),
 }
 
 impl From<jsonwebtoken::errors::Error> for Error {
   fn from(_: jsonwebtoken::errors::Error) -> Self {
     Self::JWTError
   }
 }
diff --git a/services/tunnelbroker/src/notifs/fcm/mod.rs b/services/tunnelbroker/src/notifs/fcm/mod.rs
index 6e9def31c..6666e916b 100644
--- a/services/tunnelbroker/src/notifs/fcm/mod.rs
+++ b/services/tunnelbroker/src/notifs/fcm/mod.rs
@@ -1,32 +1,33 @@
 use crate::notifs::fcm::config::FCMConfig;
 use crate::notifs::fcm::token::FCMToken;
 use std::time::Duration;
 
 pub mod config;
 mod error;
 mod firebase_message;
+mod response;
 mod token;
 
 #[derive(Clone)]
 pub struct FCMClient {
   http_client: reqwest::Client,
   config: FCMConfig,
   token: FCMToken,
 }
 
 impl FCMClient {
   pub fn new(config: &FCMConfig) -> Result<Self, error::Error> {
     let http_client = reqwest::Client::builder().build()?;
 
     // Token must be a short-lived token (60 minutes) and in a reasonable
     // timeframe.
     let token_ttl = Duration::from_secs(60 * 55);
     let token = FCMToken::new(&config.clone(), token_ttl)?;
 
     Ok(FCMClient {
       http_client,
       config: config.clone(),
       token,
     })
   }
 }
diff --git a/services/tunnelbroker/src/notifs/fcm/response.rs b/services/tunnelbroker/src/notifs/fcm/response.rs
new file mode 100644
index 000000000..190d3e93f
--- /dev/null
+++ b/services/tunnelbroker/src/notifs/fcm/response.rs
@@ -0,0 +1,44 @@
+use derive_more::{Display, Error};
+
+#[derive(PartialEq, Debug, Clone, Display, Error)]
+pub struct InvalidArgumentError {
+  pub details: String,
+}
+#[derive(PartialEq, Debug, Display, Error)]
+pub enum FCMError {
+  /// No more information is available about this error.
+  UnspecifiedError,
+
+  /// HTTP error code = 400.
+  /// Request parameters were invalid.
+  /// Potential causes include invalid registration, invalid package name,
+  /// message too big, invalid data key, invalid TTL, or other invalid
+  /// parameters.
+  InvalidArgument(InvalidArgumentError),
+
+  /// HTTP error code = 404.
+  /// App instance was unregistered from FCM. This usually means that
+  /// the token used is no longer valid and a new one must be used.
+  Unregistered,
+
+  /// HTTP error code = 403.
+  /// The authenticated sender ID is different from the sender ID for
+  /// the registration token.
+  SenderIdMismatch,
+
+  /// HTTP error code = 429.
+  /// Sending limit exceeded for the message target.
+  QuotaExceeded,
+
+  /// HTTP error code = 503.
+  /// The server is overloaded.
+  Unavailable,
+
+  /// HTTP error code = 500.
+  /// An unknown internal error occurred.
+  Internal,
+
+  /// HTTP error code = 401.
+  /// APNs certificate or web push auth key was invalid or missing.
+  ThirdPartyAuthError,
+}