diff --git a/src/lib.rs b/src/lib.rs
index 3e4caaf..f3c5031 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -28,6 +28,19 @@ pub use crate::native::now;
 #[cfg(feature = "now")]
 pub use crate::wasm::now;
 
+#[cfg(any(
+not(any(target_arch = "wasm32", target_arch = "asmjs")),
+not(any(feature = "stdweb", feature = "wasm-bindgen"))
+))]
+pub use crate::native::SystemTime;
+
+#[cfg(all(
+any(target_arch = "wasm32", target_arch = "asmjs"),
+any(feature = "stdweb", feature = "wasm-bindgen")
+))]
+pub use crate::wasm::SystemTime;
+
+
 pub use std::time::Duration;
 
 #[cfg(any(
diff --git a/src/native.rs b/src/native.rs
index 37d5da4..7deefb6 100644
--- a/src/native.rs
+++ b/src/native.rs
@@ -1,4 +1,5 @@
 pub type Instant = std::time::Instant;
+pub type SystemTime = std::time::SystemTime;
 
 /// The current time, in milliseconds.
 #[cfg(feature = "now")]
diff --git a/src/wasm.rs b/src/wasm.rs
index 24a6b7c..d0e12f7 100644
--- a/src/wasm.rs
+++ b/src/wasm.rs
@@ -101,3 +101,62 @@ pub fn now() -> f64 {
         .expect("performance should be available")
         .now()
 }
+
+#[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
+pub struct SystemTime(f64);
+
+impl SystemTime {
+    pub const UNIX_EPOCH: SystemTime = SystemTime(0.0);
+
+    pub fn now() -> SystemTime {
+        SystemTime(now())
+    }
+
+    pub fn duration_since(&self, earlier: SystemTime) -> Result<Duration, ()> {
+        let dur_ms = self.0 - earlier.0;
+        if dur_ms < 0.0 {
+            return Err(())
+        }
+        Ok(Duration::from_millis(dur_ms as u64))
+    }
+
+    pub fn elapsed(&self) -> Result<Duration, ()> {
+        self.duration_since(SystemTime::now())
+    }
+
+    pub fn checked_add(&self, duration: Duration) -> Option<SystemTime> {
+        Some(*self + duration)
+    }
+
+    pub fn checked_sub(&self, duration: Duration) -> Option<SystemTime> {
+        Some(*self - duration)
+    }
+}
+
+impl Add<Duration> for SystemTime {
+    type Output = SystemTime;
+
+    fn add(self, other: Duration) -> SystemTime {
+        SystemTime(self.0 + other.as_millis() as f64)
+    }
+}
+
+impl Sub<Duration> for SystemTime {
+    type Output = SystemTime;
+
+    fn sub(self, other: Duration) -> SystemTime {
+        SystemTime(self.0 - other.as_millis() as f64)
+    }
+}
+
+impl AddAssign<Duration> for SystemTime {
+    fn add_assign(&mut self, rhs: Duration) {
+        *self = *self + rhs;
+    }
+}
+
+impl SubAssign<Duration> for SystemTime {
+    fn sub_assign(&mut self, rhs: Duration) {
+        *self = *self - rhs;
+    }
+}
diff --git a/tests/wasm.rs b/tests/wasm.rs
index f5bfe93..e8a92ff 100644
--- a/tests/wasm.rs
+++ b/tests/wasm.rs
@@ -1,6 +1,6 @@
 extern crate wasm_bindgen_test;
 
-use instant::Instant;
+use instant::{Instant, SystemTime};
 use std::time::Duration;
 use wasm_bindgen_test::*;
 
@@ -19,3 +19,12 @@ fn test_duration() {
     let one_sec = Duration::from_secs(1);
     assert!(now.elapsed() < one_sec);
 }
+
+#[wasm_bindgen_test]
+fn test_system_time() {
+    assert!(
+        SystemTime::UNIX_EPOCH
+            .duration_since(SystemTime::now())
+            .is_err()
+    );
+}