diff --git a/src/uu/dmesg/src/dmesg.rs b/src/uu/dmesg/src/dmesg.rs
index 1343bbc..cf3f8d3 100644
--- a/src/uu/dmesg/src/dmesg.rs
+++ b/src/uu/dmesg/src/dmesg.rs
@@ -158,13 +158,10 @@ impl Dmesg<'_> {
             for record in records {
                 match self.time_format {
                     TimeFormat::Delta => {
-                        print!("[{}] ", delta_formatter.format(record.timestamp_us as i64))
+                        print!("[{}] ", delta_formatter.format(record.timestamp_us))
                     }
                     TimeFormat::Reltime => {
-                        print!(
-                            "[{}] ",
-                            reltime_formatter.format(record.timestamp_us as i64)
-                        )
+                        print!("[{}] ", reltime_formatter.format(record.timestamp_us))
                     }
                     TimeFormat::Ctime => {
                         print!("[{}] ", time_formatter::ctime(record.timestamp_us))
@@ -200,7 +197,7 @@ enum TimeFormat {
 struct Record {
     priority_facility: u32,
     _sequence: u64,
-    timestamp_us: u64,
+    timestamp_us: i64,
     message: String,
 }
 
diff --git a/src/uu/dmesg/src/json.rs b/src/uu/dmesg/src/json.rs
index 672d515..7549328 100644
--- a/src/uu/dmesg/src/json.rs
+++ b/src/uu/dmesg/src/json.rs
@@ -23,7 +23,7 @@ struct Dmesg<'a> {
 #[derive(serde::Serialize)]
 struct Record<'a> {
     pri: u32,
-    time: u64,
+    time: i64,
     msg: &'a str,
 }
 
@@ -129,11 +129,11 @@ impl serde_json::ser::Formatter for DmesgFormatter {
         }
     }
 
-    fn write_u64<W>(&mut self, writer: &mut W, value: u64) -> io::Result<()>
+    fn write_i64<W>(&mut self, writer: &mut W, value: i64) -> io::Result<()>
     where
         W: ?Sized + io::Write,
     {
-        // The only u64 field in Dmesg is time, which requires a specific format
+        // The only i64 field in Dmesg is time, which requires a specific format
         let seconds = value / 1000000;
         let sub_seconds = value % 1000000;
         let repr = format!("{:>5}.{:0>6}", seconds, sub_seconds);
diff --git a/src/uu/dmesg/src/time_formatter.rs b/src/uu/dmesg/src/time_formatter.rs
index d2d7287..c7c0e0e 100644
--- a/src/uu/dmesg/src/time_formatter.rs
+++ b/src/uu/dmesg/src/time_formatter.rs
@@ -3,22 +3,22 @@ use chrono::{DateTime, FixedOffset, TimeDelta};
 use chrono::{NaiveDate, NaiveTime};
 use std::sync::OnceLock;
 
-pub fn raw(timestamp_us: u64) -> String {
+pub fn raw(timestamp_us: i64) -> String {
     let seconds = timestamp_us / 1000000;
     let sub_seconds = timestamp_us % 1000000;
     format!("{:>5}.{:0>6}", seconds, sub_seconds)
 }
 
-pub fn ctime(timestamp_us: u64) -> String {
+pub fn ctime(timestamp_us: i64) -> String {
     let date_time = boot_time()
-        .checked_add_signed(TimeDelta::microseconds(timestamp_us as i64))
+        .checked_add_signed(TimeDelta::microseconds(timestamp_us))
         .unwrap();
     date_time.format("%a %b %d %H:%M:%S %Y").to_string()
 }
 
-pub fn iso(timestamp_us: u64) -> String {
+pub fn iso(timestamp_us: i64) -> String {
     let date_time = boot_time()
-        .checked_add_signed(TimeDelta::microseconds(timestamp_us as i64))
+        .checked_add_signed(TimeDelta::microseconds(timestamp_us))
         .unwrap();
     date_time.format("%Y-%m-%dT%H:%M:%S,%6f%:z").to_string()
 }