diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index 30d0782d..b5d90efd 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -12,6 +12,7 @@ jobs:
     strategy:
       matrix:
         go: [ '1.18' ]
+        arch: [ '', '386' ]
     name: Go ${{ matrix.go }}
     steps:
       - uses: actions/checkout@v2
@@ -19,5 +20,9 @@ jobs:
         uses: actions/setup-go@v1
         with:
           go-version: ${{ matrix.go }}
+      - name: Set GOARCH
+        run: |
+          echo "GOARCH=${{ matrix.arch }}" >> $GITHUB_ENV
       - run: go test -v -race -short ./...
+        if: env.GOARCH != '386'
       - run: go test -v ./...
diff --git a/message.go b/message.go
index 91fd1258..eb944d27 100644
--- a/message.go
+++ b/message.go
@@ -787,7 +787,7 @@ func (e *Encoder) Encode(m *Message) error {
 			return annotatef(err, "encode")
 		}
 		n := len(s.data)
-		if n > int(maxSegmentSize) {
+		if int64(n) > int64(maxSegmentSize) {
 			return errorf("encode: segment %d too large", i)
 		}
 		e.hdrbuf = appendUint32(e.hdrbuf, uint32(Size(n)/wordSize))
diff --git a/message_test.go b/message_test.go
index e3db149c..12701185 100644
--- a/message_test.go
+++ b/message_test.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"math"
 	"testing"
 	"testing/quick"
 
@@ -873,6 +874,7 @@ func TestFirstSegmentMessage_MultiSegment(t *testing.T) {
 func TestNextAlloc(t *testing.T) {
 	const max32 = 1<<31 - 8
 	const max64 = 1<<63 - 8
+	const is64bit = int64(maxInt) == math.MaxInt64
 	tests := []struct {
 		name string
 		curr int64
@@ -885,7 +887,7 @@ func TestNextAlloc(t *testing.T) {
 		{name: "first word, unaligned curr", curr: 13, max: max64, req: 8, ok: true},
 		{name: "second word", curr: 8, max: max64, req: 8, ok: true},
 		{name: "one byte pads to word", curr: 8, max: max64, req: 1, ok: true},
-		{name: "max size", curr: 0, max: max64, req: 0xfffffff8, ok: true},
+		{name: "max size", curr: 0, max: max64, req: 0xfffffff8, ok: is64bit},
 		{name: "max size + 1", curr: 0, max: max64, req: 0xfffffff9, ok: false},
 		{name: "max req", curr: 0, max: max64, req: 0xffffffff, ok: false},
 		{name: "max curr, request 0", curr: max64, max: max64, req: 0, ok: true},