diff --git a/platforms/defaults.go b/platforms/defaults.go
index cb77fbc9f..cfa3ff34a 100644
--- a/platforms/defaults.go
+++ b/platforms/defaults.go
@@ -16,27 +16,11 @@
 
 package platforms
 
-import (
-	"runtime"
-
-	specs "github.com/opencontainers/image-spec/specs-go/v1"
-)
-
 // DefaultString returns the default string specifier for the platform.
 func DefaultString() string {
 	return Format(DefaultSpec())
 }
 
-// DefaultSpec returns the current platform's default platform specification.
-func DefaultSpec() specs.Platform {
-	return specs.Platform{
-		OS:           runtime.GOOS,
-		Architecture: runtime.GOARCH,
-		// The Variant field will be empty if arch != ARM.
-		Variant: cpuVariant(),
-	}
-}
-
 // DefaultStrict returns strict form of Default.
 func DefaultStrict() MatchComparer {
 	return OnlyStrict(DefaultSpec())
diff --git a/platforms/defaults_unix.go b/platforms/defaults_unix.go
index 359063efd..e88b5b0d0 100644
--- a/platforms/defaults_unix.go
+++ b/platforms/defaults_unix.go
@@ -19,6 +19,22 @@
 
 package platforms
 
+import (
+	"runtime"
+
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// DefaultSpec returns the current platform's default platform specification.
+func DefaultSpec() specs.Platform {
+	return specs.Platform{
+		OS:           runtime.GOOS,
+		Architecture: runtime.GOARCH,
+		// The Variant field will be empty if arch != ARM.
+		Variant: cpuVariant(),
+	}
+}
+
 // Default returns the default matcher for the platform.
 func Default() MatchComparer {
 	return Only(DefaultSpec())
diff --git a/platforms/defaults_test.go b/platforms/defaults_unix_test.go
similarity index 96%
rename from platforms/defaults_test.go
rename to platforms/defaults_unix_test.go
index 62df5350d..a718c5c73 100644
--- a/platforms/defaults_test.go
+++ b/platforms/defaults_unix_test.go
@@ -1,3 +1,6 @@
+//go:build !windows
+// +build !windows
+
 /*
    Copyright The containerd Authors.
 
diff --git a/platforms/defaults_windows.go b/platforms/defaults_windows.go
index ba2c5555d..c1aaf72ca 100644
--- a/platforms/defaults_windows.go
+++ b/platforms/defaults_windows.go
@@ -27,6 +27,18 @@ import (
 	"golang.org/x/sys/windows"
 )
 
+// DefaultSpec returns the current platform's default platform specification.
+func DefaultSpec() specs.Platform {
+	major, minor, build := windows.RtlGetNtVersionNumbers()
+	return specs.Platform{
+		OS:           runtime.GOOS,
+		Architecture: runtime.GOARCH,
+		OSVersion:    fmt.Sprintf("%d.%d.%d", major, minor, build),
+		// The Variant field will be empty if arch != ARM.
+		Variant: cpuVariant(),
+	}
+}
+
 type matchComparer struct {
 	defaults        Matcher
 	osVersionPrefix string
diff --git a/platforms/defaults_windows_test.go b/platforms/defaults_windows_test.go
index 9b046700a..65256a7d9 100644
--- a/platforms/defaults_windows_test.go
+++ b/platforms/defaults_windows_test.go
@@ -17,13 +17,36 @@
 package platforms
 
 import (
+	"fmt"
+	"reflect"
+	"runtime"
 	"sort"
 	"testing"
 
 	imagespec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/stretchr/testify/assert"
+	"golang.org/x/sys/windows"
 )
 
+func TestDefault(t *testing.T) {
+	major, minor, build := windows.RtlGetNtVersionNumbers()
+	expected := imagespec.Platform{
+		OS:           runtime.GOOS,
+		Architecture: runtime.GOARCH,
+		OSVersion:    fmt.Sprintf("%d.%d.%d", major, minor, build),
+		Variant:      cpuVariant(),
+	}
+	p := DefaultSpec()
+	if !reflect.DeepEqual(p, expected) {
+		t.Fatalf("default platform not as expected: %#v != %#v", p, expected)
+	}
+
+	s := DefaultString()
+	if s != Format(p) {
+		t.Fatalf("default specifier should match formatted default spec: %v != %v", s, p)
+	}
+}
+
 func TestMatchComparerMatch(t *testing.T) {
 	m := matchComparer{
 		defaults: Only(imagespec.Platform{
@@ -36,6 +59,10 @@ func TestMatchComparerMatch(t *testing.T) {
 		platform imagespec.Platform
 		match    bool
 	}{
+		{
+			platform: DefaultSpec(),
+			match:    true,
+		},
 		{
 			platform: imagespec.Platform{
 				Architecture: "amd64",