diff --git a/src/tools/miri/src/shims/time.rs b/src/tools/miri/src/shims/time.rs
index c49aa9f20f6c..865a80251e31 100644
--- a/src/tools/miri/src/shims/time.rs
+++ b/src/tools/miri/src/shims/time.rs
@@ -275,26 +275,23 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         interp_ok(Scalar::from_i32(-1)) // Return non-zero on success
     }
 
-    #[allow(non_snake_case, clippy::arithmetic_side_effects)]
+    #[allow(clippy::arithmetic_side_effects)]
     fn system_time_since_windows_epoch(&self, time: &SystemTime) -> InterpResult<'tcx, Duration> {
-        let this = self.eval_context_ref();
-
-        let INTERVALS_PER_SEC = this.eval_windows_u64("time", "INTERVALS_PER_SEC");
-        let INTERVALS_TO_UNIX_EPOCH = this.eval_windows_u64("time", "INTERVALS_TO_UNIX_EPOCH");
-        let SECONDS_TO_UNIX_EPOCH = INTERVALS_TO_UNIX_EPOCH / INTERVALS_PER_SEC;
+        // The amount of seconds between 1601/1/1 and 1970/1/1.
+        // See https://learn.microsoft.com/en-us/windows/win32/sysinfo/converting-a-time-t-value-to-a-file-time
+        // (just divide by the number of 100 ns intervals per second).
+        const SECONDS_TO_UNIX_EPOCH: u64 = 11_644_473_600;
 
         interp_ok(system_time_to_duration(time)? + Duration::from_secs(SECONDS_TO_UNIX_EPOCH))
     }
 
     #[allow(non_snake_case, clippy::arithmetic_side_effects)]
     fn windows_ticks_for(&self, duration: Duration) -> InterpResult<'tcx, u64> {
-        let this = self.eval_context_ref();
+        // 1 interval = 100 ns.
+        // See https://learn.microsoft.com/en-us/windows/win32/api/minwinbase/ns-minwinbase-filetime
+        const NANOS_PER_INTERVAL: u128 = 100;
 
-        let NANOS_PER_SEC = this.eval_windows_u64("time", "NANOS_PER_SEC");
-        let INTERVALS_PER_SEC = this.eval_windows_u64("time", "INTERVALS_PER_SEC");
-        let NANOS_PER_INTERVAL = NANOS_PER_SEC / INTERVALS_PER_SEC;
-
-        let ticks = u64::try_from(duration.as_nanos() / u128::from(NANOS_PER_INTERVAL))
+        let ticks = u64::try_from(duration.as_nanos() / NANOS_PER_INTERVAL)
             .map_err(|_| err_unsup_format!("programs running more than 2^64 Windows ticks after the Windows epoch are not supported"))?;
         interp_ok(ticks)
     }