diff --git a/src/error.rs b/src/error.rs
index 1a3b7ac..3387c96 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -192,6 +192,9 @@ pub enum Error {
 
     #[error("tenant suspended due to invalid configuration")]
     TenantSuspended,
+
+    #[error("Payload too large: {0}")]
+    PayloadTooLarge(String),
 }
 
 impl IntoResponse for Error {
@@ -587,6 +590,12 @@ impl IntoResponse for Error {
                     message: "Request Accepted, tenant suspended due to invalid configuration".to_string(),
                 },
             ], vec![]),
+            Error::PayloadTooLarge(message) => crate::handlers::Response::new_failure(StatusCode::BAD_REQUEST, vec![
+                ResponseError {
+                    name: "payload_too_large".to_string(),
+                    message: format!("Payload too large: {}", message),
+                },
+            ], vec![]),
             e => {
                 warn!("Error does not have response clause, {:?}", e);
 
diff --git a/src/handlers/push_message.rs b/src/handlers/push_message.rs
index a6aecb7..75ae3f3 100644
--- a/src/handlers/push_message.rs
+++ b/src/handlers/push_message.rs
@@ -168,6 +168,18 @@ pub async fn handler_internal(
         )
     })?;
 
+    // Check request body size shouldn't exceed 4Kb (FCM limitations)
+    if serde_json::to_string(&body)
+        .map_err(|e| (Error::InternalSerializationError(e), None))?
+        .len()
+        > 4096
+    {
+        return Err((
+            Error::PayloadTooLarge("Request body size should not exceed 4Kb".to_string()),
+            None,
+        ));
+    };
+
     let cloned_body = body.clone();
     let push_message = if client.always_raw {
         if let Some(body) = body.raw {