diff --git a/completions.go b/completions.go
index 4687674aa..26c350907 100644
--- a/completions.go
+++ b/completions.go
@@ -101,14 +101,13 @@ func (c *Command) RegisterFlagCompletionFunc(flagName string, f func(cmd *Comman
 		return fmt.Errorf("RegisterFlagCompletionFunc: flag '%s' does not exist", flagName)
 	}
 
-	root := c.Root()
-	if _, exists := root.flagCompletionFunctions[flag]; exists {
+	if _, exists := c.flagCompletionFunctions[flag]; exists {
 		return fmt.Errorf("RegisterFlagCompletionFunc: flag '%s' already registered", flagName)
 	}
-	if root.flagCompletionFunctions == nil {
-		root.flagCompletionFunctions = map[*pflag.Flag]func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective){}
+	if c.flagCompletionFunctions == nil {
+		c.flagCompletionFunctions = map[*pflag.Flag]func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective){}
 	}
-	root.flagCompletionFunctions[flag] = f
+	c.flagCompletionFunctions[flag] = f
 	return nil
 }
 
@@ -402,7 +401,7 @@ func (c *Command) getCompletions(args []string) (*Command, []string, ShellCompDi
 	// Find the completion function for the flag or command
 	var completionFn func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective)
 	if flag != nil && flagCompletion {
-		completionFn = c.Root().flagCompletionFunctions[flag]
+		completionFn = finalCmd.flagCompletionFunctions[flag]
 	} else {
 		completionFn = finalCmd.ValidArgsFunction
 	}
diff --git a/completions_test.go b/completions_test.go
index aea06a241..9d8b073b5 100644
--- a/completions_test.go
+++ b/completions_test.go
@@ -1763,13 +1763,15 @@ func TestFlagCompletionWithNotInterspersedArgs(t *testing.T) {
 		Run:       emptyRun,
 		ValidArgs: []string{"arg1", "arg2"},
 	}
-	rootCmd.AddCommand(childCmd, childCmd2)
 	childCmd.Flags().Bool("bool", false, "test bool flag")
 	childCmd.Flags().String("string", "", "test string flag")
 	_ = childCmd.RegisterFlagCompletionFunc("string", func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective) {
 		return []string{"myval"}, ShellCompDirectiveDefault
 	})
 
+	// Important: only add the commands after RegisterFlagCompletionFunc was called
+	rootCmd.AddCommand(childCmd, childCmd2)
+
 	// Test flag completion with no argument
 	output, err := executeCommand(rootCmd, ShellCompRequestCmd, "child", "--")
 	if err != nil {
@@ -1969,6 +1971,21 @@ func TestFlagCompletionWithNotInterspersedArgs(t *testing.T) {
 	if output != expected {
 		t.Errorf("expected: %q, got: %q", expected, output)
 	}
+
+	// Test that no flag completion works on a subcmd
+	output, err = executeCommand(rootCmd, ShellCompRequestCmd, "child", "--string", "")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	expected = strings.Join([]string{
+		"myval",
+		":0",
+		"Completion ended with directive: ShellCompDirectiveDefault", ""}, "\n")
+
+	if output != expected {
+		t.Errorf("expected: %q, got: %q", expected, output)
+	}
 }
 
 func TestFlagCompletionInGoWithDesc(t *testing.T) {