diff --git a/day-4/src/main.rs b/day-4/src/main.rs
index 20778f0..7994ff9 100644
--- a/day-4/src/main.rs
+++ b/day-4/src/main.rs
@@ -17,7 +17,7 @@ fn parse_passports(input: &str) -> Result<Vec<HashMap<&str, &str>>, &str> {
                 .trim()
                 .split(|c| c == ' ' || c == '\n')
                 .map(|field| {
-                    let split = field.find(':').ok_or("Invalid passport value")?;
+                    let split = field.find(':').ok_or("Invalid passport entry; no separator")?;
                     let item = field.split_at(split);
 
                     let key = item.0;