diff --git a/cmd/compose/compose.go b/cmd/compose/compose.go
index bf30975c08..d8428e603c 100644
--- a/cmd/compose/compose.go
+++ b/cmd/compose/compose.go
@@ -47,6 +47,19 @@ import (
 	"github.com/docker/compose/v2/pkg/utils"
 )
 
+const (
+	// ComposeParallelLimit set the limit running concurrent operation on docker engine
+	ComposeParallelLimit = "COMPOSE_PARALLEL_LIMIT"
+	// ComposeProjectName define the project name to be used, instead of guessing from parent directory
+	ComposeProjectName = "COMPOSE_PROJECT_NAME"
+	// ComposeCompatibility try to mimic compose v1 as much as possible
+	ComposeCompatibility = "COMPOSE_COMPATIBILITY"
+	// ComposeRemoveOrphans remove “orphaned" containers, i.e. containers tagged for current project but not declared as service
+	ComposeRemoveOrphans = "COMPOSE_REMOVE_ORPHANS"
+	// ComposeIgnoreOrphans ignore "orphaned" containers
+	ComposeIgnoreOrphans = "COMPOSE_IGNORE_ORPHANS"
+)
+
 // Command defines a compose CLI command as a func with args
 type Command func(context.Context, []string) error
 
@@ -145,7 +158,7 @@ func (o *ProjectOptions) projectOrName(services ...string) (*types.Project, stri
 	if len(o.ConfigPaths) > 0 || o.ProjectName == "" {
 		p, err := o.ToProject(services, cli.WithDiscardEnvFile)
 		if err != nil {
-			envProjectName := os.Getenv("COMPOSE_PROJECT_NAME")
+			envProjectName := os.Getenv(ComposeProjectName)
 			if envProjectName != "" {
 				return nil, envProjectName, nil
 			}
@@ -162,7 +175,7 @@ func (o *ProjectOptions) toProjectName() (string, error) {
 		return o.ProjectName, nil
 	}
 
-	envProjectName := os.Getenv("COMPOSE_PROJECT_NAME")
+	envProjectName := os.Getenv("ComposeProjectName")
 	if envProjectName != "" {
 		return envProjectName, nil
 	}
@@ -180,7 +193,7 @@ func (o *ProjectOptions) ToProject(services []string, po ...cli.ProjectOptionsFn
 		return nil, compose.WrapComposeError(err)
 	}
 
-	if o.Compatibility || utils.StringToBool(options.Environment["COMPOSE_COMPATIBILITY"]) {
+	if o.Compatibility || utils.StringToBool(options.Environment[ComposeCompatibility]) {
 		api.Separator = "_"
 	}
 
@@ -339,10 +352,22 @@ func RootCommand(streams command.Cli, backend api.Service) *cobra.Command { //no
 					opts.EnvFiles[i] = file
 				}
 			}
-			if v, ok := os.LookupEnv("COMPOSE_PARALLEL_LIMIT"); ok && !cmd.Flags().Changed("parallel") {
+
+			composeCmd := cmd
+			for {
+				if composeCmd.Name() == PluginName {
+					break
+				}
+				if !composeCmd.HasParent() {
+					return fmt.Errorf("error parsing command line, expected %q", PluginName)
+				}
+				composeCmd = composeCmd.Parent()
+			}
+
+			if v, ok := os.LookupEnv(ComposeParallelLimit); ok && !composeCmd.Flags().Changed("parallel") {
 				i, err := strconv.Atoi(v)
 				if err != nil {
-					return fmt.Errorf("COMPOSE_PARALLEL_LIMIT must be an integer (found: %q)", v)
+					return fmt.Errorf("%s must be an integer (found: %q)", ComposeParallelLimit, v)
 				}
 				parallel = i
 			}
diff --git a/cmd/compose/down.go b/cmd/compose/down.go
index e868bbf853..29f7a7c0e6 100644
--- a/cmd/compose/down.go
+++ b/cmd/compose/down.go
@@ -62,7 +62,7 @@ func downCommand(p *ProjectOptions, backend api.Service) *cobra.Command {
 		ValidArgsFunction: noCompletion(),
 	}
 	flags := downCmd.Flags()
-	removeOrphans := utils.StringToBool(os.Getenv("COMPOSE_REMOVE_ORPHANS"))
+	removeOrphans := utils.StringToBool(os.Getenv(ComposeRemoveOrphans))
 	flags.BoolVar(&opts.removeOrphans, "remove-orphans", removeOrphans, "Remove containers for services not defined in the Compose file.")
 	flags.IntVarP(&opts.timeout, "timeout", "t", 10, "Specify a shutdown timeout in seconds")
 	flags.BoolVarP(&opts.volumes, "volumes", "v", false, "Remove named volumes declared in the `volumes` section of the Compose file and anonymous volumes attached to containers.")
diff --git a/cmd/compose/kill.go b/cmd/compose/kill.go
index de8e9b8e9e..629db5f63b 100644
--- a/cmd/compose/kill.go
+++ b/cmd/compose/kill.go
@@ -46,7 +46,7 @@ func killCommand(p *ProjectOptions, backend api.Service) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	removeOrphans := utils.StringToBool(os.Getenv("COMPOSE_REMOVE_ORPHANS"))
+	removeOrphans := utils.StringToBool(os.Getenv(ComposeRemoveOrphans))
 	flags.BoolVar(&opts.removeOrphans, "remove-orphans", removeOrphans, "Remove containers for services not defined in the Compose file.")
 	flags.StringVarP(&opts.signal, "signal", "s", "SIGKILL", "SIGNAL to send to the container.")
 
diff --git a/cmd/compose/run.go b/cmd/compose/run.go
index f454ac36d8..1a4137936f 100644
--- a/cmd/compose/run.go
+++ b/cmd/compose/run.go
@@ -146,7 +146,8 @@ func runCommand(p *ProjectOptions, streams api.Streams, backend api.Service) *co
 			if err != nil {
 				return err
 			}
-			opts.ignoreOrphans = utils.StringToBool(project.Environment["COMPOSE_IGNORE_ORPHANS"])
+
+			opts.ignoreOrphans = utils.StringToBool(project.Environment[ComposeIgnoreOrphans])
 			return runRun(ctx, backend, project, opts, createOpts, streams)
 		}),
 		ValidArgsFunction: completeServiceNames(p),
diff --git a/cmd/compose/up.go b/cmd/compose/up.go
index 37ebac9679..6894367d04 100644
--- a/cmd/compose/up.go
+++ b/cmd/compose/up.go
@@ -82,9 +82,9 @@ func upCommand(p *ProjectOptions, streams api.Streams, backend api.Service) *cob
 			return validateFlags(&up, &create)
 		}),
 		RunE: p.WithServices(func(ctx context.Context, project *types.Project, services []string) error {
-			create.ignoreOrphans = utils.StringToBool(project.Environment["COMPOSE_IGNORE_ORPHANS"])
+			create.ignoreOrphans = utils.StringToBool(project.Environment[ComposeIgnoreOrphans])
 			if create.ignoreOrphans && create.removeOrphans {
-				return fmt.Errorf("COMPOSE_IGNORE_ORPHANS and --remove-orphans cannot be combined")
+				return fmt.Errorf("%s and --remove-orphans cannot be combined", ComposeIgnoreOrphans)
 			}
 			return runUp(ctx, streams, backend, create, up, project, services)
 		}),