diff --git a/src/main.rs b/src/main.rs
index ca27c6f..f33ac5f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -203,7 +203,7 @@ fn main() {
                 }
 
                 let mut subjects = Vec::new();
-                {
+                if !uids.is_empty() {
                     let mut finish = |message: &[u8]| {
                         if message.is_empty() {
                             return;