diff --git a/cli/command/completion/functions.go b/cli/command/completion/functions.go
index 5665a274fd..2272a53ab0 100644
--- a/cli/command/completion/functions.go
+++ b/cli/command/completion/functions.go
@@ -116,14 +116,16 @@ func NetworkNames(dockerCLI APIClientProvider) cobra.CompletionFunc {
 //	export MY_VAR=hello
 //	docker run --rm --env MY_VAR alpine printenv MY_VAR
 //	hello
-func EnvVarNames(_ *cobra.Command, _ []string, _ string) (names []string, _ cobra.ShellCompDirective) {
-	envs := os.Environ()
-	names = make([]string, 0, len(envs))
-	for _, env := range envs {
-		name, _, _ := strings.Cut(env, "=")
-		names = append(names, name)
+func EnvVarNames() cobra.CompletionFunc {
+	return func(_ *cobra.Command, _ []string, _ string) (names []string, _ cobra.ShellCompDirective) {
+		envs := os.Environ()
+		names = make([]string, 0, len(envs))
+		for _, env := range envs {
+			name, _, _ := strings.Cut(env, "=")
+			names = append(names, name)
+		}
+		return names, cobra.ShellCompDirectiveNoFileComp
 	}
-	return names, cobra.ShellCompDirectiveNoFileComp
 }
 
 // FromList offers completion for the given list of options.
diff --git a/cli/command/completion/functions_test.go b/cli/command/completion/functions_test.go
index ce675ebace..7190374676 100644
--- a/cli/command/completion/functions_test.go
+++ b/cli/command/completion/functions_test.go
@@ -176,7 +176,7 @@ func TestCompleteEnvVarNames(t *testing.T) {
 		"ENV_A": "hello-a",
 		"ENV_B": "hello-b",
 	})
-	values, directives := EnvVarNames(nil, nil, "")
+	values, directives := EnvVarNames()(nil, nil, "")
 	assert.Check(t, is.Equal(directives&cobra.ShellCompDirectiveNoFileComp, cobra.ShellCompDirectiveNoFileComp), "Should not perform file completion")
 
 	sort.Strings(values)
diff --git a/cli/command/container/completion.go b/cli/command/container/completion.go
index 5cc45010f1..a9fba5a5e4 100644
--- a/cli/command/container/completion.go
+++ b/cli/command/container/completion.go
@@ -122,7 +122,7 @@ func addCompletions(cmd *cobra.Command, dockerCLI completion.APIClientProvider)
 	_ = cmd.RegisterFlagCompletionFunc("cap-add", completeLinuxCapabilityNames)
 	_ = cmd.RegisterFlagCompletionFunc("cap-drop", completeLinuxCapabilityNames)
 	_ = cmd.RegisterFlagCompletionFunc("cgroupns", completeCgroupns())
-	_ = cmd.RegisterFlagCompletionFunc("env", completion.EnvVarNames)
+	_ = cmd.RegisterFlagCompletionFunc("env", completion.EnvVarNames())
 	_ = cmd.RegisterFlagCompletionFunc("env-file", completion.FileNames)
 	_ = cmd.RegisterFlagCompletionFunc("ipc", completeIpc(dockerCLI))
 	_ = cmd.RegisterFlagCompletionFunc("link", completeLink(dockerCLI))
diff --git a/cli/command/container/exec.go b/cli/command/container/exec.go
index 48c8d5f30f..70e768373f 100644
--- a/cli/command/container/exec.go
+++ b/cli/command/container/exec.go
@@ -78,7 +78,7 @@ func newExecCommand(dockerCLI command.Cli) *cobra.Command {
 	flags.StringVarP(&options.Workdir, "workdir", "w", "", "Working directory inside the container")
 	flags.SetAnnotation("workdir", "version", []string{"1.35"})
 
-	_ = cmd.RegisterFlagCompletionFunc("env", completion.EnvVarNames)
+	_ = cmd.RegisterFlagCompletionFunc("env", completion.EnvVarNames())
 	_ = cmd.RegisterFlagCompletionFunc("env-file", completion.FileNames)
 
 	return cmd
diff --git a/cli/command/service/create.go b/cli/command/service/create.go
index 3037a7943f..ee021424d1 100644
--- a/cli/command/service/create.go
+++ b/cli/command/service/create.go
@@ -82,7 +82,7 @@ func newCreateCommand(dockerCLI command.Cli) *cobra.Command {
 	// _ = cmd.RegisterFlagCompletionFunc(flagStopSignal, completeSignals)
 
 	_ = cmd.RegisterFlagCompletionFunc(flagMode, completion.FromList("replicated", "global", "replicated-job", "global-job"))
-	_ = cmd.RegisterFlagCompletionFunc(flagEnv, completion.EnvVarNames) // TODO(thaJeztah): flagEnvRemove (needs to read current env-vars on the service)
+	_ = cmd.RegisterFlagCompletionFunc(flagEnv, completion.EnvVarNames()) // TODO(thaJeztah): flagEnvRemove (needs to read current env-vars on the service)
 	_ = cmd.RegisterFlagCompletionFunc(flagEnvFile, completion.FileNames)
 	_ = cmd.RegisterFlagCompletionFunc(flagNetwork, completion.NetworkNames(dockerCLI))
 	_ = cmd.RegisterFlagCompletionFunc(flagRestartCondition, completion.FromList("none", "on-failure", "any"))
diff --git a/cli/command/service/update.go b/cli/command/service/update.go
index e51c037c71..b1e56a7934 100644
--- a/cli/command/service/update.go
+++ b/cli/command/service/update.go
@@ -121,7 +121,7 @@ func newUpdateCommand(dockerCLI command.Cli) *cobra.Command {
 	// _ = cmd.RegisterFlagCompletionFunc(flagCapDrop, completeLinuxCapabilityNames)
 	// _ = cmd.RegisterFlagCompletionFunc(flagStopSignal, completeSignals)
 
-	_ = cmd.RegisterFlagCompletionFunc(flagEnvAdd, completion.EnvVarNames)
+	_ = cmd.RegisterFlagCompletionFunc(flagEnvAdd, completion.EnvVarNames())
 	// TODO(thaJeztah): flagEnvRemove (needs to read current env-vars on the service)
 	_ = cmd.RegisterFlagCompletionFunc("image", completion.ImageNames(dockerCLI, -1))
 	_ = cmd.RegisterFlagCompletionFunc(flagNetworkAdd, completion.NetworkNames(dockerCLI))