diff --git a/go.mod b/go.mod
index d7065bc..e143ab9 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module github.com/sapcc/ntp_exporter
 go 1.22
 
 require (
-	github.com/beevik/ntp v1.4.1
+	github.com/beevik/ntp v1.4.2
 	github.com/prometheus/client_golang v1.19.1
 	github.com/sapcc/go-api-declarations v1.11.2
 	github.com/sapcc/go-bits v0.0.0-20240516084938-1c041b7a84ce
diff --git a/go.sum b/go.sum
index f35d9da..9160a06 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,5 @@
-github.com/beevik/ntp v1.4.1 h1:wbs1dC82GEcSk7LjDog3kMEZuiOk8M7tePUsZaTCvXY=
-github.com/beevik/ntp v1.4.1/go.mod h1:zkATLTt8VUZuOfYX2KgOnir4yvtAxWbnUUA24umXFnc=
+github.com/beevik/ntp v1.4.2 h1:cjYhZqczanf6br/ocViahE75ipj7CmKQAh7fSBaCNK4=
+github.com/beevik/ntp v1.4.2/go.mod h1:zkATLTt8VUZuOfYX2KgOnir4yvtAxWbnUUA24umXFnc=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
diff --git a/vendor/github.com/beevik/ntp/CONTRIBUTORS b/vendor/github.com/beevik/ntp/CONTRIBUTORS
index 714817a..f984471 100644
--- a/vendor/github.com/beevik/ntp/CONTRIBUTORS
+++ b/vendor/github.com/beevik/ntp/CONTRIBUTORS
@@ -7,3 +7,4 @@ Leonid Evdokimov (darkk)
 Ask Bjørn Hansen (abh)
 Al Cutter (AlCutter)
 Silves-Xiang (silves-xiang)
+Andrey Smirnov (smira)
diff --git a/vendor/github.com/beevik/ntp/RELEASE_NOTES.md b/vendor/github.com/beevik/ntp/RELEASE_NOTES.md
index c696225..f53ad47 100644
--- a/vendor/github.com/beevik/ntp/RELEASE_NOTES.md
+++ b/vendor/github.com/beevik/ntp/RELEASE_NOTES.md
@@ -1,3 +1,10 @@
+Release v1.4.2
+==============
+
+**Fixes**
+
+* Fixed a bug in clock offset calculation.
+
 Release v1.4.1
 ==============
 
diff --git a/vendor/github.com/beevik/ntp/ntp.go b/vendor/github.com/beevik/ntp/ntp.go
index 0d25544..8306ffa 100644
--- a/vendor/github.com/beevik/ntp/ntp.go
+++ b/vendor/github.com/beevik/ntp/ntp.go
@@ -749,9 +749,18 @@ func rtt(org, rec, xmt, dst ntpTime) time.Duration {
 func offset(org, rec, xmt, dst ntpTime) time.Duration {
 	// local clock offset
 	//   offset = ((rec-org) + (xmt-dst)) / 2
-	a := rec.Time().Sub(org.Time())
-	b := xmt.Time().Sub(dst.Time())
-	return (a + b) / time.Duration(2)
+	// The inputs are 64-bit unsigned ints. The output is a 63-bit signed int.
+	// Need to handle conversions with care. See:
+	// https://www.eecis.udel.edu/~mills/time.html
+	a := int64(rec) - int64(org)
+	b := int64(xmt) - int64(dst)
+	d := (a + b) / 2
+
+	if d > 0 {
+		return ntpTime(d).Duration()
+	} else {
+		return -ntpTime(-d).Duration()
+	}
 }
 
 func minError(org, rec, xmt, dst ntpTime) time.Duration {
diff --git a/vendor/modules.txt b/vendor/modules.txt
index d4ea0a9..8d77672 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -1,4 +1,4 @@
-# github.com/beevik/ntp v1.4.1
+# github.com/beevik/ntp v1.4.2
 ## explicit; go 1.17
 github.com/beevik/ntp
 # github.com/beorn7/perks v1.0.1