diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
index 9e3ec441..5b62d9e5 100644
--- a/src/decoder/mod.rs
+++ b/src/decoder/mod.rs
@@ -206,7 +206,7 @@ fn decode_bson<R: Read + ?Sized>(reader: &mut R, tag: u8, utf8_lossy: bool) -> D
             // The int64 is UTC milliseconds since the Unix epoch.
             let time = read_i64(reader)?;
 
-            match Utc.timestamp_opt(time / 1000, ((time % 1000) as u32).saturating_mul(1_000_000)) {
+            match Utc.timestamp_opt(time / 1000, ((time % 1000) as u32) * 1_000_000) {
                 LocalResult::None => Err(DecoderError::InvalidTimestamp(time)),
                 LocalResult::Ambiguous(..) => Err(DecoderError::AmbiguousTimestamp(time)),
                 LocalResult::Single(t) => Ok(Bson::UtcDatetime(t)),
diff --git a/src/encoder/mod.rs b/src/encoder/mod.rs
index 83589a7c..b7c0673a 100644
--- a/src/encoder/mod.rs
+++ b/src/encoder/mod.rs
@@ -130,7 +130,7 @@ fn encode_bson<W: Write + ?Sized>(writer: &mut W, key: &str, val: &Bson) -> Enco
             writer.write_u8(From::from(subtype))?;
             writer.write_all(data).map_err(From::from)
         }
-        &Bson::UtcDatetime(ref v) => write_i64(writer, (v.timestamp() * 1000) + (v.nanosecond() / 1000000) as i64),
+        &Bson::UtcDatetime(ref v) => write_i64(writer, (v.timestamp() * 1000) + (v.nanosecond() / 1_000_000) as i64),
         &Bson::Null => Ok(()),
         &Bson::Symbol(ref v) => write_string(writer, &v),
     }
diff --git a/tests/lib.rs b/tests/lib.rs
index 0459225a..7d1f2b15 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -1,5 +1,6 @@
 #[macro_use(bson, doc)]
 extern crate bson;
+extern crate byteorder;
 extern crate chrono;
 extern crate hex;
 
diff --git a/tests/modules/encoder_decoder.rs b/tests/modules/encoder_decoder.rs
index 076d1177..b11c9e9e 100644
--- a/tests/modules/encoder_decoder.rs
+++ b/tests/modules/encoder_decoder.rs
@@ -1,9 +1,10 @@
-use bson::{decode_document, encode_document, Bson, decode_document_utf8_lossy};
 use bson::oid::ObjectId;
 use bson::spec::BinarySubtype;
-use chrono::Utc;
+use bson::{decode_document, decode_document_utf8_lossy, encode_document, Bson};
+use byteorder::{LittleEndian, WriteBytesExt};
 use chrono::offset::TimeZone;
-use std::io::Cursor;
+use chrono::Utc;
+use std::io::{Cursor, Write};
 
 #[test]
 fn test_encode_decode_floating_point() {
@@ -277,3 +278,21 @@ fn test_encode_decode_symbol() {
     let decoded = decode_document(&mut Cursor::new(buf)).unwrap();
     assert_eq!(decoded, doc);
 }
+
+#[test]
+fn test_decode_utc_date_time_overflows() {
+    let t = 1530492218 * 1_000 + 999;
+
+    let mut raw0 = vec![0x09, b'A', 0x00];
+    raw0.write_i64::<LittleEndian>(t).unwrap();
+
+    let mut raw = vec![];
+    raw.write_i32::<LittleEndian>((raw0.len() + 4 + 1) as i32).unwrap();
+    raw.write_all(&raw0).unwrap();
+    raw.write_u8(0).unwrap();
+
+    let decoded = decode_document(&mut Cursor::new(raw)).unwrap();
+
+    let expected = doc! { "A" => Utc.timestamp(1530492218, 999 * 1_000_000)};
+    assert_eq!(decoded, expected);
+}