diff --git a/internal/system/acl.go b/internal/system/acl.go
index f8f1dc6..efc4884 100644
--- a/internal/system/acl.go
+++ b/internal/system/acl.go
@@ -9,16 +9,20 @@ import (
 )
 
 // UpdatePerm appends an ephemeral acl update Op.
-func (sys *I) UpdatePerm(path string, perms ...acl.Perm) {
+func (sys *I) UpdatePerm(path string, perms ...acl.Perm) *I {
 	sys.UpdatePermType(Process, path, perms...)
+
+	return sys
 }
 
 // UpdatePermType appends an acl update Op.
-func (sys *I) UpdatePermType(et Enablement, path string, perms ...acl.Perm) {
+func (sys *I) UpdatePermType(et Enablement, path string, perms ...acl.Perm) *I {
 	sys.lock.Lock()
 	defer sys.lock.Unlock()
 
 	sys.ops = append(sys.ops, &ACL{et, path, perms})
+
+	return sys
 }
 
 type ACL struct {
diff --git a/internal/system/mkdir.go b/internal/system/mkdir.go
index 0f3787f..c868bee 100644
--- a/internal/system/mkdir.go
+++ b/internal/system/mkdir.go
@@ -9,19 +9,23 @@ import (
 )
 
 // Ensure the existence and mode of a directory.
-func (sys *I) Ensure(name string, perm os.FileMode) {
+func (sys *I) Ensure(name string, perm os.FileMode) *I {
 	sys.lock.Lock()
 	defer sys.lock.Unlock()
 
 	sys.ops = append(sys.ops, &Mkdir{User, name, perm, false})
+
+	return sys
 }
 
 // Ephemeral ensures the temporary existence and mode of a directory through the life of et.
-func (sys *I) Ephemeral(et Enablement, name string, perm os.FileMode) {
+func (sys *I) Ephemeral(et Enablement, name string, perm os.FileMode) *I {
 	sys.lock.Lock()
 	defer sys.lock.Unlock()
 
 	sys.ops = append(sys.ops, &Mkdir{et, name, perm, true})
+
+	return sys
 }
 
 type Mkdir struct {
diff --git a/internal/system/tmpfiles.go b/internal/system/tmpfiles.go
index 9215bd3..7300f30 100644
--- a/internal/system/tmpfiles.go
+++ b/internal/system/tmpfiles.go
@@ -12,44 +12,50 @@ import (
 )
 
 // CopyFile registers an Op that copies path dst from src.
-func (sys *I) CopyFile(dst, src string) {
-	sys.CopyFileType(Process, dst, src)
+func (sys *I) CopyFile(dst, src string) *I {
+	return sys.CopyFileType(Process, dst, src)
 }
 
 // CopyFileType registers a file copying Op labelled with type et.
-func (sys *I) CopyFileType(et Enablement, dst, src string) {
+func (sys *I) CopyFileType(et Enablement, dst, src string) *I {
 	sys.lock.Lock()
 	sys.ops = append(sys.ops, &Tmpfile{et, tmpfileCopy, dst, src})
 	sys.lock.Unlock()
 
 	sys.UpdatePermType(et, dst, acl.Read)
+
+	return sys
 }
 
 // Link registers an Op that links dst to src.
-func (sys *I) Link(oldname, newname string) {
-	sys.LinkFileType(Process, oldname, newname)
+func (sys *I) Link(oldname, newname string) *I {
+	return sys.LinkFileType(Process, oldname, newname)
 }
 
 // LinkFileType registers a file linking Op labelled with type et.
-func (sys *I) LinkFileType(et Enablement, oldname, newname string) {
+func (sys *I) LinkFileType(et Enablement, oldname, newname string) *I {
 	sys.lock.Lock()
 	defer sys.lock.Unlock()
 
 	sys.ops = append(sys.ops, &Tmpfile{et, tmpfileLink, newname, oldname})
+
+	return sys
 }
 
 // Write registers an Op that writes dst with the contents of src.
-func (sys *I) Write(dst, src string) {
-	sys.WriteType(Process, dst, src)
+func (sys *I) Write(dst, src string) *I {
+	return sys.WriteType(Process, dst, src)
 }
 
 // WriteType registers a file writing Op labelled with type et.
-func (sys *I) WriteType(et Enablement, dst, src string) {
+func (sys *I) WriteType(et Enablement, dst, src string) *I {
 	sys.lock.Lock()
 	sys.ops = append(sys.ops, &Tmpfile{et, tmpfileWrite, dst, src})
 	sys.lock.Unlock()
 
 	sys.UpdatePermType(et, dst, acl.Read)
+
+	return sys
 }
 
 const (
diff --git a/internal/system/xhost.go b/internal/system/xhost.go
index 51c8d24..3046394 100644
--- a/internal/system/xhost.go
+++ b/internal/system/xhost.go
@@ -8,11 +8,13 @@ import (
 )
 
 // ChangeHosts appends an X11 ChangeHosts command Op.
-func (sys *I) ChangeHosts(username string) {
+func (sys *I) ChangeHosts(username string) *I {
 	sys.lock.Lock()
 	defer sys.lock.Unlock()
 
 	sys.ops = append(sys.ops, XHost(username))
+
+	return sys
 }
 
 type XHost string