diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7ea0a6..d4de0b9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,11 +8,15 @@
 
 ### Changed
 - `Float64Flag`, `IntFlag`, and `DurationFlag` default values are no longer
-quoted in help text output.
+  quoted in help text output.
 - All flag types now include `(default: {value})` strings following usage when a
-default value can be (reasonably) detected.
+  default value can be (reasonably) detected.
 - `IntSliceFlag` and `StringSliceFlag` usage strings are now more consistent
-with non-slice flag types
+  with non-slice flag types
+- Apps now exit with a code of 3 if an unknown subcommand is specified
+  (previously they printed "No help topic for...", but still exited 0. This
+  makes it easier to script around apps built using `cli` since they can trust
+  that a 0 exit code indicated a successful execution.
 
 ## [1.16.0] - 2016-05-02
 ### Added
diff --git a/help.go b/help.go
index 45e8603..259e452 100644
--- a/help.go
+++ b/help.go
@@ -81,10 +81,10 @@ var helpCommand = Command{
 	Action: func(c *Context) error {
 		args := c.Args()
 		if args.Present() {
-			ShowCommandHelp(c, args.First())
-		} else {
-			ShowAppHelp(c)
+			return ShowCommandHelp(c, args.First())
 		}
+
+		ShowAppHelp(c)
 		return nil
 	},
 }
@@ -97,11 +97,10 @@ var helpSubcommand = Command{
 	Action: func(c *Context) error {
 		args := c.Args()
 		if args.Present() {
-			ShowCommandHelp(c, args.First())
-		} else {
-			ShowSubcommandHelp(c)
+			return ShowCommandHelp(c, args.First())
 		}
-		return nil
+
+		return ShowSubcommandHelp(c)
 	},
 }
 
@@ -127,30 +126,31 @@ func DefaultAppComplete(c *Context) {
 }
 
 // Prints help for the given command
-func ShowCommandHelp(ctx *Context, command string) {
+func ShowCommandHelp(ctx *Context, command string) error {
 	// show the subcommand help for a command with subcommands
 	if command == "" {
 		HelpPrinter(ctx.App.Writer, SubcommandHelpTemplate, ctx.App)
-		return
+		return nil
 	}
 
 	for _, c := range ctx.App.Commands {
 		if c.HasName(command) {
 			HelpPrinter(ctx.App.Writer, CommandHelpTemplate, c)
-			return
+			return nil
 		}
 	}
 
-	if ctx.App.CommandNotFound != nil {
-		ctx.App.CommandNotFound(ctx, command)
-	} else {
-		fmt.Fprintf(ctx.App.Writer, "No help topic for '%v'\n", command)
+	if ctx.App.CommandNotFound == nil {
+		return NewExitError(fmt.Sprintf("No help topic for '%v'", command), 3)
 	}
+
+	ctx.App.CommandNotFound(ctx, command)
+	return nil
 }
 
 // Prints help for the given subcommand
-func ShowSubcommandHelp(c *Context) {
-	ShowCommandHelp(c, c.Command.Name)
+func ShowSubcommandHelp(c *Context) error {
+	return ShowCommandHelp(c, c.Command.Name)
 }
 
 // Prints the version number of the App
diff --git a/help_test.go b/help_test.go
index ee5c25c..0fabdba 100644
--- a/help_test.go
+++ b/help_test.go
@@ -2,6 +2,8 @@ package cli
 
 import (
 	"bytes"
+	"flag"
+	"strings"
 	"testing"
 )
 
@@ -110,3 +112,59 @@ func Test_Version_Custom_Flags(t *testing.T) {
 		t.Errorf("unexpected output: %s", output.String())
 	}
 }
+
+func Test_helpCommand_Action_ErrorIfNoTopic(t *testing.T) {
+	app := NewApp()
+
+	set := flag.NewFlagSet("test", 0)
+	set.Parse([]string{"foo"})
+
+	c := NewContext(app, set, nil)
+
+	err := helpCommand.Action.(func(*Context) error)(c)
+
+	if err == nil {
+		t.Fatalf("expected error from helpCommand.Action(), but got nil")
+	}
+
+	exitErr, ok := err.(*ExitError)
+	if !ok {
+		t.Fatalf("expected ExitError from helpCommand.Action(), but instead got: %v", err.Error())
+	}
+
+	if !strings.HasPrefix(exitErr.Error(), "No help topic for") {
+		t.Fatalf("expected an unknown help topic error, but got: %v", exitErr.Error())
+	}
+
+	if exitErr.exitCode != 3 {
+		t.Fatalf("expected exit value = 3, got %d instead", exitErr.exitCode)
+	}
+}
+
+func Test_helpSubcommand_Action_ErrorIfNoTopic(t *testing.T) {
+	app := NewApp()
+
+	set := flag.NewFlagSet("test", 0)
+	set.Parse([]string{"foo"})
+
+	c := NewContext(app, set, nil)
+
+	err := helpSubcommand.Action.(func(*Context) error)(c)
+
+	if err == nil {
+		t.Fatalf("expected error from helpCommand.Action(), but got nil")
+	}
+
+	exitErr, ok := err.(*ExitError)
+	if !ok {
+		t.Fatalf("expected ExitError from helpCommand.Action(), but instead got: %v", err.Error())
+	}
+
+	if !strings.HasPrefix(exitErr.Error(), "No help topic for") {
+		t.Fatalf("expected an unknown help topic error, but got: %v", exitErr.Error())
+	}
+
+	if exitErr.exitCode != 3 {
+		t.Fatalf("expected exit value = 3, got %d instead", exitErr.exitCode)
+	}
+}