diff --git a/image/config.go b/image/config.go
index 160f435..0778b06 100644
--- a/image/config.go
+++ b/image/config.go
@@ -66,11 +66,19 @@ func findConfig(w walker, d *v1.Descriptor) (*config, error) {
 }
 
 func (c *config) runtimeSpec(rootfs string) (*specs.Spec, error) {
-	if c.OS != "linux" {
+	var s specs.Spec
+
+	switch c.OS {
+	case "linux":
+		s.Linux = &specs.Linux{}
+	case "solaris":
+		s.Solaris = &specs.Solaris{}
+	case "windows":
+		s.Windows = &specs.Windows{}
+	default:
 		return nil, fmt.Errorf("%s: unsupported OS", c.OS)
 	}
 
-	var s specs.Spec
 	s.Version = specs.Version
 	// we should at least apply the default spec, otherwise this is totally useless
 	s.Process.Terminal = true
@@ -106,8 +114,6 @@ func (c *config) runtimeSpec(rootfs string) (*specs.Spec, error) {
 		return nil, errors.New("config.User: unsupported format")
 	}
 
-	s.Linux = &specs.Linux{}
-
 	for vol := range c.Config.Volumes {
 		s.Mounts = append(
 			s.Mounts,