diff --git a/helper/export_test.go b/helper/export_test.go
deleted file mode 100644
index 6bf18ce..0000000
--- a/helper/export_test.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package helper
-
-import (
-	"os"
-	"os/exec"
-	"testing"
-)
-
-// replace execCommand to have the resulting *exec.Cmd launch TestHelperChildStub
-func ReplaceExecCommand(t *testing.T) {
-	t.Cleanup(func() {
-		execCommand = exec.Command
-	})
-
-	execCommand = func(name string, arg ...string) *exec.Cmd {
-		return exec.Command(os.Args[0], append([]string{"-test.run=TestHelperChildStub", "--", name}, arg...)...)
-	}
-}
diff --git a/helper/helper_test.go b/helper/helper_test.go
index 6b27e68..2caada4 100644
--- a/helper/helper_test.go
+++ b/helper/helper_test.go
@@ -35,7 +35,7 @@ func prepareArgs() {
 }
 
 func TestHelper_StartNotify_Close_Wait(t *testing.T) {
-	helper.ReplaceExecCommand(t)
+	helper.InternalReplaceExecCommand(t)
 	argsOnce.Do(prepareArgs)
 
 	t.Run("start helper with status channel", func(t *testing.T) {
@@ -106,7 +106,7 @@ func TestHelper_StartNotify_Close_Wait(t *testing.T) {
 	})
 }
 func TestHelper_Start_Close_Wait(t *testing.T) {
-	helper.ReplaceExecCommand(t)
+	helper.InternalReplaceExecCommand(t)
 	argsOnce.Do(prepareArgs)
 
 	var wt io.WriterTo
diff --git a/helper/stub.go b/helper/stub.go
new file mode 100644
index 0000000..32dc11e
--- /dev/null
+++ b/helper/stub.go
@@ -0,0 +1,90 @@
+package helper
+
+import (
+	"io"
+	"os"
+	"os/exec"
+	"strconv"
+	"syscall"
+	"testing"
+)
+
+// InternalChildStub is an internal function but exported because it is cross-package;
+// it is part of the implementation of the helper stub.
+func InternalChildStub() {
+	// this test mocks the helper process
+	if os.Getenv(FortifyHelper) != "1" {
+		return
+	}
+
+	// simulate args pipe behaviour
+	func() {
+		f := os.NewFile(3, "|0")
+		if f == nil {
+			panic("attempted to start helper without args pipe")
+		}
+
+		if _, err := io.Copy(os.Stdout, f); err != nil {
+			panic("cannot read args: " + err.Error())
+		}
+	}()
+
+	var wait chan struct{}
+
+	// simulate status pipe behaviour
+	if os.Getenv(FortifyStatus) == "1" {
+		wait = make(chan struct{})
+		go func() {
+			f := os.NewFile(4, "|1")
+			if f == nil {
+				panic("attempted to start with status reporting without status pipe")
+			}
+
+			if _, err := f.Write([]byte{'x'}); err != nil {
+				panic("cannot write to status pipe: " + err.Error())
+			}
+
+			// wait for status pipe close
+			var epoll int
+			if fd, err := syscall.EpollCreate1(0); err != nil {
+				panic("cannot open epoll fd: " + err.Error())
+			} else {
+				defer func() {
+					if err = syscall.Close(fd); err != nil {
+						panic("cannot close epoll fd: " + err.Error())
+					}
+				}()
+				epoll = fd
+			}
+			if err := syscall.EpollCtl(epoll, syscall.EPOLL_CTL_ADD, int(f.Fd()), &syscall.EpollEvent{}); err != nil {
+				panic("cannot add status pipe to epoll: " + err.Error())
+			}
+			events := make([]syscall.EpollEvent, 1)
+			if _, err := syscall.EpollWait(epoll, events, -1); err != nil {
+				panic("cannot poll status pipe: " + err.Error())
+			}
+			if events[0].Events != syscall.EPOLLERR {
+				panic(strconv.Itoa(int(events[0].Events)))
+
+			}
+			close(wait)
+		}()
+	}
+
+	if wait != nil {
+		<-wait
+	}
+}
+
+// InternalReplaceExecCommand is an internal function but exported because it is cross-package;
+// it is part of the implementation of the helper stub.
+func InternalReplaceExecCommand(t *testing.T) {
+	t.Cleanup(func() {
+		execCommand = exec.Command
+	})
+
+	// replace execCommand to have the resulting *exec.Cmd launch TestHelperChildStub
+	execCommand = func(name string, arg ...string) *exec.Cmd {
+		return exec.Command(os.Args[0], append([]string{"-test.run=TestHelperChildStub", "--", name}, arg...)...)
+	}
+}
diff --git a/helper/stub_test.go b/helper/stub_test.go
index 9f85ac6..5838c10 100644
--- a/helper/stub_test.go
+++ b/helper/stub_test.go
@@ -1,75 +1,11 @@
 package helper_test
 
 import (
-	"io"
-	"os"
-	"strconv"
-	"syscall"
 	"testing"
 
 	"git.ophivana.moe/cat/fortify/helper"
 )
 
 func TestHelperChildStub(t *testing.T) {
-	// this test mocks the helper process
-	if os.Getenv(helper.FortifyHelper) != "1" {
-		return
-	}
-	// simulate args pipe behaviour
-	func() {
-		f := os.NewFile(3, "|0")
-		if f == nil {
-			panic("attempted to start helper without args pipe")
-		}
-
-		if _, err := io.Copy(os.Stdout, f); err != nil {
-			panic("cannot read args: " + err.Error())
-		}
-	}()
-
-	var wait chan struct{}
-
-	// simulate status pipe behaviour
-	if os.Getenv(helper.FortifyStatus) == "1" {
-		wait = make(chan struct{})
-		go func() {
-			f := os.NewFile(4, "|1")
-			if f == nil {
-				panic("attempted to start with status reporting without status pipe")
-			}
-
-			if _, err := f.Write([]byte{'x'}); err != nil {
-				panic("cannot write to status pipe: " + err.Error())
-			}
-
-			// wait for status pipe close
-			var epoll int
-			if fd, err := syscall.EpollCreate1(0); err != nil {
-				panic("cannot open epoll fd: " + err.Error())
-			} else {
-				defer func() {
-					if err = syscall.Close(fd); err != nil {
-						panic("cannot close epoll fd: " + err.Error())
-					}
-				}()
-				epoll = fd
-			}
-			if err := syscall.EpollCtl(epoll, syscall.EPOLL_CTL_ADD, int(f.Fd()), &syscall.EpollEvent{}); err != nil {
-				panic("cannot add status pipe to epoll: " + err.Error())
-			}
-			events := make([]syscall.EpollEvent, 1)
-			if _, err := syscall.EpollWait(epoll, events, -1); err != nil {
-				panic("cannot poll status pipe: " + err.Error())
-			}
-			if events[0].Events != syscall.EPOLLERR {
-				panic(strconv.Itoa(int(events[0].Events)))
-
-			}
-			close(wait)
-		}()
-	}
-
-	if wait != nil {
-		<-wait
-	}
+	helper.InternalChildStub()
 }