diff --git a/pkg/runner/local_runner.go b/pkg/runner/local_runner.go
index 71dede8f..a6558900 100644
--- a/pkg/runner/local_runner.go
+++ b/pkg/runner/local_runner.go
@@ -91,7 +91,7 @@ func (r *localRunner) openLog(logPath string) (filesystem.FileAppender, error) {
 // exec.Cmd in localRunner.Run(). It may use different strategies for
 // resolving the paths of argv[0] and the working directory, depending
 // on whether the action needs to be run in a chroot() or not.
-type CommandCreator func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectory, pathVariable string) (*exec.Cmd, error)
+type CommandCreator func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectoryParser path.Parser, pathVariable string) (*exec.Cmd, error)
 
 // NewLocalRunner returns a Runner capable of running commands on the
 // local system directly.
@@ -118,7 +118,12 @@ func (r *localRunner) Run(ctx context.Context, request *runner.RunRequest) (*run
 		return nil, util.StatusWrap(err, "Failed to resolve input root directory")
 	}
 
-	cmd, err := r.commandCreator(ctx, request.Arguments, inputRootDirectory, request.WorkingDirectory, request.EnvironmentVariables["PATH"])
+	workingDirectoryParser, err := path.NewUNIXParser(request.WorkingDirectory)
+	if err != nil {
+		return nil, util.StatusWrap(err, "Invalid working directory")
+	}
+
+	cmd, err := r.commandCreator(ctx, request.Arguments, inputRootDirectory, workingDirectoryParser, request.EnvironmentVariables["PATH"])
 	if err != nil {
 		return nil, err
 	}
diff --git a/pkg/runner/local_runner_unix.go b/pkg/runner/local_runner_unix.go
index e31d6fc7..a01d3195 100644
--- a/pkg/runner/local_runner_unix.go
+++ b/pkg/runner/local_runner_unix.go
@@ -90,11 +90,7 @@ func lookupExecutable(workingDirectory *path.Builder, pathVariable, argv0 string
 // NewPlainCommandCreator returns a CommandCreator for cases where we don't
 // need to chroot into the input root directory.
 func NewPlainCommandCreator(sysProcAttr *syscall.SysProcAttr) CommandCreator {
-	return func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectoryStr, pathVariable string) (*exec.Cmd, error) {
-		workingDirectoryParser, err := path.NewUNIXParser(workingDirectoryStr)
-		if err != nil {
-			return nil, util.StatusWrap(err, "Invalid working directory")
-		}
+	return func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectoryParser path.Parser, pathVariable string) (*exec.Cmd, error) {
 		workingDirectory, scopeWalker := inputRootDirectory.Join(path.VoidScopeWalker)
 		if err := path.Resolve(workingDirectoryParser, scopeWalker); err != nil {
 			return nil, util.StatusWrap(err, "Failed to resolve working directory")
@@ -121,7 +117,7 @@ func NewPlainCommandCreator(sysProcAttr *syscall.SysProcAttr) CommandCreator {
 // NewChrootedCommandCreator returns a CommandCreator for cases where we
 // need to chroot into the input root directory.
 func NewChrootedCommandCreator(sysProcAttr *syscall.SysProcAttr) (CommandCreator, error) {
-	return func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectoryStr, pathVariable string) (*exec.Cmd, error) {
+	return func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectoryParser path.Parser, pathVariable string) (*exec.Cmd, error) {
 		// The addition of /usr/bin/env is necessary as the PATH resolution
 		// will take place prior to the chroot, so the executable may not be
 		// found by exec.LookPath() inside exec.CommandContext() and may
@@ -134,10 +130,6 @@ func NewChrootedCommandCreator(sysProcAttr *syscall.SysProcAttr) (CommandCreator
 
 		// Set the working relative to be relative to the root
 		// directory of the chrooted environment.
-		workingDirectoryParser, err := path.NewUNIXParser(workingDirectoryStr)
-		if err != nil {
-			return nil, util.StatusWrap(err, "Invalid working directory")
-		}
 		workingDirectory, scopeWalker := path.RootBuilder.Join(path.VoidScopeWalker)
 		if err := path.Resolve(workingDirectoryParser, scopeWalker); err != nil {
 			return nil, util.StatusWrap(err, "Failed to resolve working directory")
diff --git a/pkg/runner/local_runner_windows.go b/pkg/runner/local_runner_windows.go
index aacc92ef..860836cf 100644
--- a/pkg/runner/local_runner_windows.go
+++ b/pkg/runner/local_runner_windows.go
@@ -23,7 +23,7 @@ import (
 // NewPlainCommandCreator returns a CommandCreator for cases where we don't
 // need to chroot into the input root directory.
 func NewPlainCommandCreator(sysProcAttr *syscall.SysProcAttr) CommandCreator {
-	return func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectoryStr, pathVariable string) (*exec.Cmd, error) {
+	return func(ctx context.Context, arguments []string, inputRootDirectory *path.Builder, workingDirectoryParser path.Parser, pathVariable string) (*exec.Cmd, error) {
 		// TODO: This may not work correctly if the action sets
 		// the PATH environment variable explicitly.
 		cmd := exec.CommandContext(ctx, arguments[0], arguments[1:]...)
@@ -32,7 +32,7 @@ func NewPlainCommandCreator(sysProcAttr *syscall.SysProcAttr) CommandCreator {
 		// Set the working relative to be relative to the input
 		// root directory.
 		workingDirectory, scopeWalker := inputRootDirectory.Join(path.VoidScopeWalker)
-		if err := path.Resolve(workingDirectoryStr, scopeWalker); err != nil {
+		if err := path.Resolve(workingDirectoryParser, scopeWalker); err != nil {
 			return nil, util.StatusWrap(err, "Failed to resolve working directory")
 		}
 		cmd.Dir = filepath.FromSlash(workingDirectory.String())