diff --git a/src/builder.rs b/src/builder.rs
index 3094e76..7a33a03 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -66,9 +66,9 @@ impl<'a> Builder<'a> {
                 return Err(Error::StartTimeAheadOfCurrentTime(start_time));
             }
 
-            to_sonyflake_time(start_time)
+            to_sonyflake_time(start_time)?
         } else {
-            to_sonyflake_time(Utc.with_ymd_and_hms(2014, 9, 1, 0, 0, 0).unwrap())
+            to_sonyflake_time(Utc.with_ymd_and_hms(2014, 9, 1, 0, 0, 0).unwrap())?
         };
 
         let machine_id = if let Some(machine_id) = self.machine_id {
diff --git a/src/error.rs b/src/error.rs
index e5d2e52..10bbf05 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -20,4 +20,6 @@ pub enum Error {
     NoPrivateIPv4,
     #[error("mutex is poisoned (i.e. a panic happened while it was locked)")]
     MutexPoisoned,
+    #[error("failed to get current time")]
+    FailedToGetCurrentTime,
 }
diff --git a/src/sonyflake.rs b/src/sonyflake.rs
index df61c91..178cc29 100644
--- a/src/sonyflake.rs
+++ b/src/sonyflake.rs
@@ -56,7 +56,7 @@ impl Sonyflake {
     pub fn next_id(&self) -> Result<u64, Error> {
         let mut internals = self.0.internals.lock().map_err(|_| Error::MutexPoisoned)?;
 
-        let current = current_elapsed_time(self.0.start_time);
+        let current = current_elapsed_time(self.0.start_time)?;
         if internals.elapsed_time < current {
             internals.elapsed_time = current;
             internals.sequence = 0;
@@ -66,7 +66,7 @@ impl Sonyflake {
             if internals.sequence == 0 {
                 internals.elapsed_time += 1;
                 let overtime = internals.elapsed_time - current;
-                thread::sleep(sleep_time(overtime));
+                thread::sleep(sleep_time(overtime)?);
             }
         }
 
@@ -91,17 +91,25 @@ impl Clone for Sonyflake {
 
 const SONYFLAKE_TIME_UNIT: i64 = 10_000_000; // nanoseconds, i.e. 10msec
 
-pub(crate) fn to_sonyflake_time(time: DateTime<Utc>) -> i64 {
-    time.timestamp_nanos() / SONYFLAKE_TIME_UNIT
+pub(crate) fn to_sonyflake_time(time: DateTime<Utc>) -> Result<i64, Error> {
+    Ok(time
+        .timestamp_nanos_opt()
+        .ok_or(Error::FailedToGetCurrentTime)?
+        / SONYFLAKE_TIME_UNIT)
 }
 
-fn current_elapsed_time(start_time: i64) -> i64 {
-    to_sonyflake_time(Utc::now()) - start_time
+fn current_elapsed_time(start_time: i64) -> Result<i64, Error> {
+    Ok(to_sonyflake_time(Utc::now())? - start_time)
 }
 
-fn sleep_time(overtime: i64) -> Duration {
-    Duration::from_millis(overtime as u64 * 10)
-        - Duration::from_nanos((Utc::now().timestamp_nanos() % SONYFLAKE_TIME_UNIT) as u64)
+fn sleep_time(overtime: i64) -> Result<Duration, Error> {
+    Ok(Duration::from_millis(overtime as u64 * 10)
+        - Duration::from_nanos(
+            (Utc::now()
+                .timestamp_nanos_opt()
+                .ok_or(Error::FailedToGetCurrentTime)?
+                % SONYFLAKE_TIME_UNIT) as u64,
+        ))
 }
 
 pub struct DecomposedSonyflake {
diff --git a/src/tests.rs b/src/tests.rs
index 280de25..3ed9f51 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -52,7 +52,7 @@ fn test_once() -> Result<(), BoxDynError> {
 #[test]
 fn test_run_for_10s() -> Result<(), BoxDynError> {
     let now = Utc::now();
-    let start_time = to_sonyflake_time(now);
+    let start_time = to_sonyflake_time(now)?;
     let sf = Sonyflake::builder().start_time(now).finalize()?;
 
     let mut last_id: u64 = 0;
@@ -60,7 +60,7 @@ fn test_run_for_10s() -> Result<(), BoxDynError> {
 
     let machine_id = lower_16_bit_private_ip()? as u64;
 
-    let initial = to_sonyflake_time(Utc::now());
+    let initial = to_sonyflake_time(Utc::now())?;
     let mut current = initial.clone();
     while current - initial < 1000 {
         let id = sf.next_id()?;
@@ -71,7 +71,7 @@ fn test_run_for_10s() -> Result<(), BoxDynError> {
         }
         last_id = id;
 
-        current = to_sonyflake_time(Utc::now());
+        current = to_sonyflake_time(Utc::now())?;
 
         let actual_msb = parts.msb;
         if actual_msb != 0 {