diff --git a/completions.go b/completions.go
index 4687674aa3..26c3509077 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
 	}