diff --git a/crates/zoxide-engine/src/dir.rs b/crates/zoxide-engine/src/dir.rs
index c613c30..5d24738 100644
--- a/crates/zoxide-engine/src/dir.rs
+++ b/crates/zoxide-engine/src/dir.rs
@@ -25,7 +25,7 @@ impl Dir {
         const DAY: Epoch = 24 * HOUR;
         const WEEK: Epoch = 7 * DAY;
 
-        let duration = now - self.last_accessed;
+        let duration = now.saturating_sub(self.last_accessed);
         if duration < HOUR {
             self.rank * 4.0
         } else if duration < DAY {
@@ -39,4 +39,4 @@ impl Dir {
 }
 
 pub type Rank = f64;
-pub type Epoch = i64; // use a signed integer so subtraction can be performed on it
+pub type Epoch = u64;
diff --git a/src/util.rs b/src/util.rs
index 73a0024..6bb2066 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -21,7 +21,7 @@ pub fn current_time() -> Result<Epoch> {
         .context("system clock set to invalid time")?
         .as_secs();
 
-    Ok(current_time as _)
+    Ok(current_time)
 }
 
 pub fn path_to_str<P: AsRef<Path>>(path: &P) -> Result<&str> {