diff --git a/com/stream.go b/com/stream.go
index b0f7b9d..b2c4bdf 100644
--- a/com/stream.go
+++ b/com/stream.go
@@ -179,103 +179,6 @@ func (o SequentialStream) Write(b []byte) (int, error) {
 	return p.Write(b)
 }
 
-func (abi *IStreamABI) Seek(offset int64, whence int) (n int64, _ error) {
-	var hr wingoes.HRESULT
-	method := unsafe.Slice(abi.Vtbl, 14)[5]
-
-	if runtime.GOARCH == "386" {
-		words := (*[2]uintptr)(unsafe.Pointer(&offset))
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			words[0],
-			words[1],
-			uintptr(uint32(whence)),
-			uintptr(unsafe.Pointer(&n)),
-		)
-		hr = wingoes.HRESULT(rc)
-	} else {
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			uintptr(offset),
-			uintptr(uint32(whence)),
-			uintptr(unsafe.Pointer(&n)),
-		)
-		hr = wingoes.HRESULT(rc)
-	}
-
-	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
-		return 0, e
-	}
-
-	return n, nil
-}
-
-func (abi *IStreamABI) SetSize(newSize uint64) error {
-	var hr wingoes.HRESULT
-	method := unsafe.Slice(abi.Vtbl, 14)[6]
-
-	if runtime.GOARCH == "386" {
-		words := (*[2]uintptr)(unsafe.Pointer(&newSize))
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			words[0],
-			words[1],
-		)
-		hr = wingoes.HRESULT(rc)
-	} else {
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			uintptr(newSize),
-		)
-		hr = wingoes.HRESULT(rc)
-	}
-
-	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
-		return e
-	}
-
-	return nil
-}
-
-func (abi *IStreamABI) CopyTo(dest *IStreamABI, numBytesToCopy uint64) (bytesRead, bytesWritten uint64, _ error) {
-	var hr wingoes.HRESULT
-	method := unsafe.Slice(abi.Vtbl, 14)[7]
-
-	if runtime.GOARCH == "386" {
-		words := (*[2]uintptr)(unsafe.Pointer(&numBytesToCopy))
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			uintptr(unsafe.Pointer(dest)),
-			words[0],
-			words[1],
-			uintptr(unsafe.Pointer(&bytesRead)),
-			uintptr(unsafe.Pointer(&bytesWritten)),
-		)
-		hr = wingoes.HRESULT(rc)
-	} else {
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			uintptr(unsafe.Pointer(dest)),
-			uintptr(numBytesToCopy),
-			uintptr(unsafe.Pointer(&bytesRead)),
-			uintptr(unsafe.Pointer(&bytesWritten)),
-		)
-		hr = wingoes.HRESULT(rc)
-	}
-
-	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
-		return bytesRead, bytesWritten, e
-	}
-
-	return bytesRead, bytesWritten, nil
-}
-
 func (abi *IStreamABI) Commit(flags STGC) error {
 	method := unsafe.Slice(abi.Vtbl, 14)[8]
 
@@ -306,76 +209,6 @@ func (abi *IStreamABI) Revert() error {
 	return nil
 }
 
-func (abi *IStreamABI) LockRegion(offset, numBytes uint64, lockType LOCKTYPE) error {
-	var hr wingoes.HRESULT
-	method := unsafe.Slice(abi.Vtbl, 14)[10]
-
-	if runtime.GOARCH == "386" {
-		oWords := (*[2]uintptr)(unsafe.Pointer(&offset))
-		nWords := (*[2]uintptr)(unsafe.Pointer(&numBytes))
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			oWords[0],
-			oWords[1],
-			nWords[0],
-			nWords[1],
-			uintptr(lockType),
-		)
-		hr = wingoes.HRESULT(rc)
-	} else {
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			uintptr(offset),
-			uintptr(numBytes),
-			uintptr(lockType),
-		)
-		hr = wingoes.HRESULT(rc)
-	}
-
-	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
-		return e
-	}
-
-	return nil
-}
-
-func (abi *IStreamABI) UnlockRegion(offset, numBytes uint64, lockType LOCKTYPE) error {
-	var hr wingoes.HRESULT
-	method := unsafe.Slice(abi.Vtbl, 14)[11]
-
-	if runtime.GOARCH == "386" {
-		oWords := (*[2]uintptr)(unsafe.Pointer(&offset))
-		nWords := (*[2]uintptr)(unsafe.Pointer(&numBytes))
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			oWords[0],
-			oWords[1],
-			nWords[0],
-			nWords[1],
-			uintptr(lockType),
-		)
-		hr = wingoes.HRESULT(rc)
-	} else {
-		rc, _, _ := syscall.SyscallN(
-			method,
-			uintptr(unsafe.Pointer(abi)),
-			uintptr(offset),
-			uintptr(numBytes),
-			uintptr(lockType),
-		)
-		hr = wingoes.HRESULT(rc)
-	}
-
-	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
-		return e
-	}
-
-	return nil
-}
-
 func (abi *IStreamABI) Stat(flags STATFLAG) (*STATSTG, error) {
 	result := new(STATSTG)
 	method := unsafe.Slice(abi.Vtbl, 14)[12]
diff --git a/com/stream_386.go b/com/stream_386.go
new file mode 100644
index 0000000..6737941
--- /dev/null
+++ b/com/stream_386.go
@@ -0,0 +1,130 @@
+// Copyright (c) 2023 Tailscale Inc & AUTHORS. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+
+package com
+
+import (
+	"math"
+	"syscall"
+	"unsafe"
+
+	"github.com/dblohm7/wingoes"
+)
+
+const maxStreamRWLen = math.MaxInt32
+
+func (abi *IStreamABI) Seek(offset int64, whence int) (n int64, _ error) {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[5]
+
+	words := (*[2]uintptr)(unsafe.Pointer(&offset))
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		words[0],
+		words[1],
+		uintptr(uint32(whence)),
+		uintptr(unsafe.Pointer(&n)),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return 0, e
+	}
+
+	return n, nil
+}
+
+func (abi *IStreamABI) SetSize(newSize uint64) error {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[6]
+
+	words := (*[2]uintptr)(unsafe.Pointer(&newSize))
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		words[0],
+		words[1],
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return e
+	}
+
+	return nil
+}
+
+func (abi *IStreamABI) CopyTo(dest *IStreamABI, numBytesToCopy uint64) (bytesRead, bytesWritten uint64, _ error) {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[7]
+
+	words := (*[2]uintptr)(unsafe.Pointer(&numBytesToCopy))
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		uintptr(unsafe.Pointer(dest)),
+		words[0],
+		words[1],
+		uintptr(unsafe.Pointer(&bytesRead)),
+		uintptr(unsafe.Pointer(&bytesWritten)),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return bytesRead, bytesWritten, e
+	}
+
+	return bytesRead, bytesWritten, nil
+}
+
+func (abi *IStreamABI) LockRegion(offset, numBytes uint64, lockType LOCKTYPE) error {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[10]
+
+	oWords := (*[2]uintptr)(unsafe.Pointer(&offset))
+	nWords := (*[2]uintptr)(unsafe.Pointer(&numBytes))
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		oWords[0],
+		oWords[1],
+		nWords[0],
+		nWords[1],
+		uintptr(lockType),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return e
+	}
+
+	return nil
+}
+
+func (abi *IStreamABI) UnlockRegion(offset, numBytes uint64, lockType LOCKTYPE) error {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[11]
+
+	oWords := (*[2]uintptr)(unsafe.Pointer(&offset))
+	nWords := (*[2]uintptr)(unsafe.Pointer(&numBytes))
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		oWords[0],
+		oWords[1],
+		nWords[0],
+		nWords[1],
+		uintptr(lockType),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return e
+	}
+
+	return nil
+}
diff --git a/com/stream_not386.go b/com/stream_not386.go
index 7b82a40..a0593f6 100644
--- a/com/stream_not386.go
+++ b/com/stream_not386.go
@@ -8,6 +8,109 @@ package com
 
 import (
 	"math"
+	"syscall"
+	"unsafe"
+
+	"github.com/dblohm7/wingoes"
 )
 
 const maxStreamRWLen = math.MaxUint32
+
+func (abi *IStreamABI) Seek(offset int64, whence int) (n int64, _ error) {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[5]
+
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		uintptr(offset),
+		uintptr(uint32(whence)),
+		uintptr(unsafe.Pointer(&n)),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return 0, e
+	}
+
+	return n, nil
+}
+
+func (abi *IStreamABI) SetSize(newSize uint64) error {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[6]
+
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		uintptr(newSize),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return e
+	}
+
+	return nil
+}
+
+func (abi *IStreamABI) CopyTo(dest *IStreamABI, numBytesToCopy uint64) (bytesRead, bytesWritten uint64, _ error) {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[7]
+
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		uintptr(unsafe.Pointer(dest)),
+		uintptr(numBytesToCopy),
+		uintptr(unsafe.Pointer(&bytesRead)),
+		uintptr(unsafe.Pointer(&bytesWritten)),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return bytesRead, bytesWritten, e
+	}
+
+	return bytesRead, bytesWritten, nil
+}
+
+func (abi *IStreamABI) LockRegion(offset, numBytes uint64, lockType LOCKTYPE) error {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[10]
+
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		uintptr(offset),
+		uintptr(numBytes),
+		uintptr(lockType),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return e
+	}
+
+	return nil
+}
+
+func (abi *IStreamABI) UnlockRegion(offset, numBytes uint64, lockType LOCKTYPE) error {
+	var hr wingoes.HRESULT
+	method := unsafe.Slice(abi.Vtbl, 14)[11]
+
+	rc, _, _ := syscall.SyscallN(
+		method,
+		uintptr(unsafe.Pointer(abi)),
+		uintptr(offset),
+		uintptr(numBytes),
+		uintptr(lockType),
+	)
+	hr = wingoes.HRESULT(rc)
+
+	if e := wingoes.ErrorFromHRESULT(hr); e.Failed() {
+		return e
+	}
+
+	return nil
+}
diff --git a/com/stream_test.go b/com/stream_test.go
index 67037ef..9297c52 100644
--- a/com/stream_test.go
+++ b/com/stream_test.go
@@ -47,7 +47,7 @@ func memoryStream(t *testing.T, useLegacy bool) {
 	// Only try this on supported 64-bit archs so that the test doesn't run the
 	// risk of crashing due to OOM.
 	if runtime.GOARCH != "386" {
-		tooBig := make([]byte, maxStreamRWLen+1)
+		tooBig := getTooBigSlice()
 		_, err = newMemoryStreamInternal(tooBig, useLegacy)
 		if err == nil {
 			t.Errorf("Unexpected success creating too-large memory stream")
diff --git a/com/stream_test_386.go b/com/stream_test_386.go
new file mode 100644
index 0000000..5dfaa8f
--- /dev/null
+++ b/com/stream_test_386.go
@@ -0,0 +1,11 @@
+// Copyright (c) 2024 Tailscale Inc & AUTHORS. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+
+package com
+
+func getTooBigSlice() []byte {
+	return nil
+}
diff --git a/com/stream_test_not386.go b/com/stream_test_not386.go
new file mode 100644
index 0000000..9a3db1b
--- /dev/null
+++ b/com/stream_test_not386.go
@@ -0,0 +1,11 @@
+// Copyright (c) 2024 Tailscale Inc & AUTHORS. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows && !386
+
+package com
+
+func getTooBigSlice() []byte {
+	return make([]byte, maxStreamRWLen+1)
+}