diff --git a/moon.mod b/moon.mod
index c0c0ee8..9bed861 100644
--- a/moon.mod
+++ b/moon.mod
@@ -18,6 +18,4 @@ description = "MoonBit SDK for making Firefly Zero games"
 
 preferred_target = "wasm"
 
-options(
-  source: "src",
-)
+source = "src"
diff --git a/src/internal/ffi/misc.mbt b/src/internal/ffi/misc.mbt
index 2749bd4..476a9e5 100644
--- a/src/internal/ffi/misc.mbt
+++ b/src/internal/ffi/misc.mbt
@@ -14,6 +14,9 @@ pub fn set_seed(seed : UInt) = "misc" "set_seed"
 /// Get a random value.
 pub fn get_random() -> UInt = "misc" "get_random"
 
+///|
+pub fn get_time() -> Int64 = "misc" "get_time"
+
 ///|
 /// Get name of the device.
 pub fn get_name(peer : Int, buf : UInt) -> Int = "misc" "get_name"
diff --git a/src/misc.mbt b/src/misc.mbt
index f1f17cf..5de01ef 100644
--- a/src/misc.mbt
+++ b/src/misc.mbt
@@ -76,6 +76,11 @@ pub fn get_random() -> UInt {
   @ffi.get_random()
 }
 
+///|
+pub fn get_time() -> Duration {
+  { us: @ffi.get_time() }
+}
+
 ///|
 /// Get name of the device.
 pub fn get_name(peer : Peer) -> Utf8 {
diff --git a/src/misc_duration.mbt b/src/misc_duration.mbt
new file mode 100644
index 0000000..8d6c407
--- /dev/null
+++ b/src/misc_duration.mbt
@@ -0,0 +1,48 @@
+///|
+pub(all) struct Duration {
+  us : Int64
+} derive(Eq, Compare, Hash)
+
+///|
+pub fn Duration::from_microseconds(us : Int64) -> Duration {
+  { us, }
+}
+
+///|
+pub fn Duration::from_milliseconds(ms : Int64) -> Duration {
+  { us: ms * 1000 }
+}
+
+///|
+pub fn Duration::from_seconds(s : Int64) -> Duration {
+  { us: s * 1_000_000 }
+}
+
+///|
+/// Add two durations.
+pub fn Duration::add(self : Duration, rhs : Duration) -> Duration {
+  Duration::{ us: self.us + rhs.us }
+}
+
+///|
+/// The duration as an integer microsecond count.
+pub fn Duration::to_microseconds(self : Duration) -> Int64 {
+  self.us
+}
+
+///|
+/// The duration as an integer millisecond count.
+pub fn Duration::to_milliseconds(self : Duration) -> Int64 {
+  self.to_microseconds() / 1000
+}
+
+///|
+/// The duration as an integer second count.
+pub fn Duration::to_seconds(self : Duration) -> Int64 {
+  self.to_milliseconds() / 1000
+}
+
+///|
+pub impl Neg for Duration with fn neg(self) -> Duration {
+  { us: -self.us }
+}