diff --git a/cmd/strelaysrv/status.go b/cmd/strelaysrv/status.go
index f6052250..a9aaca8a 100644
--- a/cmd/strelaysrv/status.go
+++ b/cmd/strelaysrv/status.go
@@ -86,9 +86,9 @@ func getStatus(w http.ResponseWriter, r *http.Request) {
 }
 
 type rateCalculator struct {
+	counter   *int64 // atomic, must remain 64-bit aligned
 	rates     []int64
 	prev      int64
-	counter   *int64
 	startTime time.Time
 }
 
diff --git a/lib/protocol/counting.go b/lib/protocol/counting.go
index d441ed31..2310e91f 100644
--- a/lib/protocol/counting.go
+++ b/lib/protocol/counting.go
@@ -10,8 +10,8 @@ import (
 
 type countingReader struct {
 	io.Reader
-	tot  int64 // bytes
-	last int64 // unix nanos
+	tot  int64 // bytes (atomic, must remain 64-bit aligned)
+	last int64 // unix nanos (atomic, must remain 64-bit aligned)
 }
 
 var (
@@ -37,8 +37,8 @@ func (c *countingReader) Last() time.Time {
 
 type countingWriter struct {
 	io.Writer
-	tot  int64 // bytes
-	last int64 // unix nanos
+	tot  int64 // bytes (atomic, must remain 64-bit aligned)
+	last int64 // unix nanos (atomic, must remain 64-bit aligned)
 }
 
 func (c *countingWriter) Write(bs []byte) (int, error) {
diff --git a/lib/scanner/walk.go b/lib/scanner/walk.go
index c89bbcd0..58d66c38 100644
--- a/lib/scanner/walk.go
+++ b/lib/scanner/walk.go
@@ -537,7 +537,7 @@ func (w *walker) handleError(ctx context.Context, context, path string, err erro
 // A byteCounter gets bytes added to it via Update() and then provides the
 // Total() and one minute moving average Rate() in bytes per second.
 type byteCounter struct {
-	total int64
+	total int64 // atomic, must remain 64-bit aligned
 	metrics.EWMA
 	stop chan struct{}
 }
diff --git a/lib/stun/stun.go b/lib/stun/stun.go
index f2b299ce..16ae0bdd 100644
--- a/lib/stun/stun.go
+++ b/lib/stun/stun.go
@@ -39,7 +39,7 @@ const (
 )
 
 type writeTrackingPacketConn struct {
-	lastWrite int64
+	lastWrite int64 // atomic, must remain 64-bit aligned
 	net.PacketConn
 }