diff --git a/src/main.rs b/src/main.rs
index 7c53d67..c6581ab 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -101,7 +101,12 @@ fn log(f: &String, since: &Option<String>) -> Result<(), String> {
 fn parse_time(since: &Option<String>) -> Result<SystemTime, String> {
    match since {
       Some(since) => {
-         Err("not impl".to_string())
+         match DateTime::parse_from_str(since, "%Y-%m-%d") {
+            Ok(dt) => {
+               Err("not impl".to_string())
+            },
+            Err(msg) => Err(format!("failed to parse {}: {}", since, msg)),
+         }
       },
       None => Ok(SystemTime::now().sub(Duration::from_secs(60*60*24*7))),
    }