diff --git a/src/interval.rs b/src/interval.rs
index 3f0d459..871cea3 100644
--- a/src/interval.rs
+++ b/src/interval.rs
@@ -44,21 +44,21 @@ impl Unit
     fn multiplier(&self) -> u64 {
 	use lazy_static::lazy_static;
 	use std::collections::HashMap;
+
 	
-	use Unit::*;
-	lazy_static! {
-	    static ref MUL_TABLE: HashMap<Unit, u64> = {
-		let mut map = HashMap::with_capacity(8);
-		map.insert(Second,  1000); 
-		map.insert(Minute,  Second.multiplier() * 60);
-		map.insert(Hour,  Minute.multiplier() * 60);
-		map.insert(Day,  Hour.multiplier() * 24);
-		map.insert(Week,  Day.multiplier() * 7);
-		map.insert(Year,  Week.multiplier() * 52);
-		map.insert(Aeon,  Year.multiplier() * 1000000);
-		map
-	    };
+	fn calc_table(&self) -> {
+	    use Unit::*;
+	    match self {
+		Second => 1000,
+		Minute => Second.multiplier() * 60,
+		Hour => Minute.multiplier() * 60,
+		Day => Hour.multiplier() * 24,
+		Week => Day.multiplier() * 7,
+		Year => Week.multiplier() * 52,
+		Aeon => Year.multiplier() * 1000000,
+	    }
 	}
+	
 	*MUL_TABLE.get(&self).unwrap()
     }
 }
diff --git a/src/sys/mod.rs b/src/sys/mod.rs
new file mode 100644
index 0000000..c5d584a
--- /dev/null
+++ b/src/sys/mod.rs
@@ -0,0 +1,2 @@
+use super::*;
+