diff --git a/boot.go b/boot.go
index f775140..f68d683 100644
--- a/boot.go
+++ b/boot.go
@@ -1,10 +1,17 @@
 package treerack
 
-import "os"
+import (
+	"bytes"
+	"os"
+)
 
 func bootSyntax() (*Syntax, error) {
-	f, _ := os.Open("syntax.treerack")
-	defer f.Close()
+	b, err := os.ReadFile("syntax.treerack")
+	if err != nil {
+		return nil, err
+	}
+
+	buf := bytes.NewBuffer(b)
 	s := &Syntax{}
-	return s, s.ReadSyntax(f)
+	return s, s.ReadSyntax(buf)
 }
diff --git a/boot_test.go b/boot_test.go
index 7b1d74f..469b232 100644
--- a/boot_test.go
+++ b/boot_test.go
@@ -1,16 +1,13 @@
 package treerack
 
 import (
+	"bytes"
 	"io"
 	"os"
 	"testing"
 )
 
-func parseWithSyntax(s *Syntax, f io.ReadSeeker) (Node, error) {
-	if _, err := f.Seek(0, 0); err != nil {
-		return Node{}, err
-	}
-
+func parseWithSyntax(s *Syntax, f io.Reader) (Node, error) {
 	return s.Parse(f)
 }
 
@@ -27,7 +24,7 @@ func syntaxFromTree(n Node) (*Syntax, error) {
 	return s, nil
 }
 
-func testParseFromTree(t *testing.T, n Node, f io.ReadSeeker) Node {
+func testParseFromTree(t *testing.T, n Node, f io.Reader) Node {
 	s, err := syntaxFromTree(n)
 	if err != nil {
 		t.Error(err)
@@ -45,31 +42,27 @@ func testParseFromTree(t *testing.T, n Node, f io.ReadSeeker) Node {
 }
 
 func TestBoot(t *testing.T) {
-	t.Skip()
 	b, err := bootSyntax()
 	if err != nil {
 		t.Error(err)
 		return
 	}
 
-	f, err := os.Open("syntax.treerack")
+	p, err := os.ReadFile("syntax.treerack")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	n0, err := parseWithSyntax(b, bytes.NewBuffer(p))
 	if err != nil {
 		t.Error(err)
 		return
 	}
 
-	defer f.Close()
-
-	n0, err := parseWithSyntax(b, f)
-	if err != nil {
-		t.Error(err)
-		return
-	}
-
-	n1 := testParseFromTree(t, n0, f)
+	n1 := testParseFromTree(t, n0, bytes.NewBuffer(p))
 	if t.Failed() {
 		return
 	}
 
-	testParseFromTree(t, n1, f)
+	testParseFromTree(t, n1, bytes.NewBuffer(p))
 }
diff --git a/cmd/treerack/check.go b/cmd/treerack/check.go
index 1da0029..7369f15 100644
--- a/cmd/treerack/check.go
+++ b/cmd/treerack/check.go
@@ -30,18 +30,16 @@ type checkOptions struct {
 // Syntax can be provided via a filename option or an inline string option. Input can be provided via a filename
 // option, a positional argument filename, an inline string option, or piped from standard input.
 func check(o checkOptions, stdin io.Reader, args ...string) error {
-	syntax, finalizeSyntax, err := initInput(o.Syntax, o.SyntaxString, nil, nil)
+	syntax, err := initInput(o.Syntax, o.SyntaxString, nil, nil)
 	if err != nil {
 		return err
 	}
 
-	defer finalizeSyntax()
-	input, finalizeInput, err := initInput(o.Input, o.InputString, stdin, args)
+	input, err := initInput(o.Input, o.InputString, stdin, args)
 	if err != nil {
 		return err
 	}
 
-	defer finalizeInput()
 	mtl := defaultMaxTraceLength
 	if o.MaxTraceLength != nil {
 		mtl = *o.MaxTraceLength
diff --git a/cmd/treerack/checksyntax.go b/cmd/treerack/checksyntax.go
index 9145b9b..0e88615 100644
--- a/cmd/treerack/checksyntax.go
+++ b/cmd/treerack/checksyntax.go
@@ -25,12 +25,11 @@ type checkSyntaxOptions struct {
 // checkSyntax validates a syntax definition. The syntax may be provided via a file path (using an option or a
 // positional argument), an inline string, or piped from standard input.
 func checkSyntax(o checkSyntaxOptions, stdin io.Reader, args ...string) error {
-	syntax, finalize, err := initInput(o.Syntax, o.SyntaxString, stdin, args)
+	syntax, err := initInput(o.Syntax, o.SyntaxString, stdin, args)
 	if err != nil {
 		return err
 	}
 
-	defer finalize()
 	mtl := defaultMaxTraceLength
 	if o.MaxTraceLength != nil {
 		mtl = *o.MaxTraceLength
diff --git a/cmd/treerack/generate.go b/cmd/treerack/generate.go
index 061fa3a..3f5303f 100644
--- a/cmd/treerack/generate.go
+++ b/cmd/treerack/generate.go
@@ -32,12 +32,11 @@ type generateOptions struct {
 // The syntax may be provided via a file path (using an option or a positional argument), an
 // inline string, or piped from standard input.
 func generate(o generateOptions, stdin io.Reader, stdout io.Writer, args ...string) error {
-	syntax, finalizeSyntax, err := initInput(o.Syntax, o.SyntaxString, stdin, args)
+	syntax, err := initInput(o.Syntax, o.SyntaxString, stdin, args)
 	if err != nil {
 		return err
 	}
 
-	defer finalizeSyntax()
 	mtl := defaultMaxTraceLength
 	if o.MaxTraceLength != nil {
 		mtl = *o.MaxTraceLength
diff --git a/cmd/treerack/input.go b/cmd/treerack/input.go
index 29c8c65..a177750 100644
--- a/cmd/treerack/input.go
+++ b/cmd/treerack/input.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"io"
-	"log"
 	"os"
 )
 
@@ -16,13 +15,7 @@ var (
 
 func noop() {}
 
-func initInput(
-	filename, stringValue *string, stdin io.Reader, args []string,
-) (
-	input io.Reader, finalize func(), err error,
-) {
-	finalize = noop
-
+func initInput(filename, stringValue *string, stdin io.Reader, args []string) (input io.Reader, err error) {
 	var inputCount int
 	if filename != nil {
 		inputCount++
@@ -53,19 +46,12 @@ func initInput(
 			return
 		}
 
-		var f io.ReadCloser
-		f, err = os.Open(*filename)
-		if err != nil {
+		var b []byte
+		if b, err = os.ReadFile(*filename); err != nil {
 			return
 		}
 
-		finalize = func() {
-			if err := f.Close(); err != nil {
-				log.Fatalln(err)
-			}
-		}
-
-		input = f
+		input = bytes.NewBuffer(b)
 	case stringValue != nil:
 		input = bytes.NewBufferString(*stringValue)
 	default:
diff --git a/cmd/treerack/show.go b/cmd/treerack/show.go
index 6aa2d7a..8bf84e4 100644
--- a/cmd/treerack/show.go
+++ b/cmd/treerack/show.go
@@ -64,18 +64,16 @@ func mapNode(n treerack.Node) node {
 // provided via a filename option, a positional argument filename, an inline string option, or piped from
 // standard input.
 func show(o showOptions, stdin io.Reader, stdout io.Writer, args ...string) error {
-	syntax, finalizeSyntax, err := initInput(o.Syntax, o.SyntaxString, nil, nil)
+	syntax, err := initInput(o.Syntax, o.SyntaxString, nil, nil)
 	if err != nil {
 		return err
 	}
 
-	defer finalizeSyntax()
-	input, finalizeInput, err := initInput(o.Input, o.InputString, stdin, args)
+	input, err := initInput(o.Input, o.InputString, stdin, args)
 	if err != nil {
 		return err
 	}
 
-	defer finalizeInput()
 	mtl := defaultMaxTraceLength
 	if o.MaxTraceLength != nil {
 		mtl = *o.MaxTraceLength
diff --git a/makefile b/makefile
index 8898b46..475b2e1 100644
--- a/makefile
+++ b/makefile
@@ -130,12 +130,18 @@ cover-cmd: .coverprofile-cmd
 showcover-cmd: .coverprofile-cmd
 	go tool cover -html .coverprofile-cmd
 
-cpu.out: $(sources)
-	go test -v -run TestMMLFile -cpuprofile cpu.out
+cpu.out: $(sources) $(parsers)
+	go test -v -count 1 -run TestMMLFile -cpuprofile cpu.out
 
 cpu: cpu.out
 	go tool pprof -top cpu.out
 
+mem.out: $(sources) $(parsers)
+	go test -v -count 1 -run TestMMLFile -memprofile mem.out
+
+mem: mem.out
+	go tool pprof -top mem.out
+
 fmt: $(sources) $(parsers) head.gen.go headexported.gen.go internal/self/self.gen.go cmd/treerack/docreflect.gen.go
 	go fmt ./...
 	go run script/format.go $(parsers)
diff --git a/mmlexp_test.go b/mmlexp_test.go
index ce587fa..ca12a4f 100644
--- a/mmlexp_test.go
+++ b/mmlexp_test.go
@@ -2,7 +2,6 @@ package treerack
 
 import (
 	"bytes"
-	"io"
 	"os"
 	"testing"
 	"time"
@@ -2995,32 +2994,18 @@ func TestMMLFile(t *testing.T) {
 
 	s.Init()
 
-	f, err := os.Open("doc/example/test.mml")
+	b, err := os.ReadFile("doc/example/test.mml")
 	if err != nil {
-		t.Error(err)
-		return
+		t.Fatal(err)
 	}
 
-	defer f.Close()
-
 	var d time.Duration
 	for i := 0; i < n && !t.Failed(); i++ {
 		func() {
-			if _, err := f.Seek(0, 0); err != nil {
-				t.Error(err)
-				return
-			}
-
-			b := bytes.NewBuffer(nil)
-			if _, err := io.Copy(b, f); err != nil {
-				t.Error(err)
-				return
-			}
-
+			buf := bytes.NewBuffer(b)
 			start := time.Now()
-			_, err = s.Parse(b)
+			_, err = s.Parse(buf)
 			d += time.Now().Sub(start)
-
 			if err != nil {
 				t.Error(err)
 			}
diff --git a/open_test.go b/open_test.go
index b439c29..ee94027 100644
--- a/open_test.go
+++ b/open_test.go
@@ -30,13 +30,13 @@ func openSyntaxReader(r io.Reader) (*Syntax, error) {
 }
 
 func openSyntaxFile(file string) (*Syntax, error) {
-	f, err := os.Open(file)
+	b, err := os.ReadFile(file)
 	if err != nil {
 		return nil, err
 	}
 
-	defer f.Close()
-	return openSyntaxReader(f)
+	r := bytes.NewBuffer(b)
+	return openSyntaxReader(r)
 }
 
 func openSyntaxString(syntax string) (*Syntax, error) {
diff --git a/script/createhead.go b/script/createhead.go
index 7c39f46..afc5327 100644
--- a/script/createhead.go
+++ b/script/createhead.go
@@ -111,13 +111,12 @@ func main() {
 
 	var files []io.Reader
 	for _, fn := range flag.Args() {
-		f, err := os.Open(fn)
+		b, err := os.ReadFile(fn)
 		if err != nil {
 			log.Fatalln(err)
 		}
 
-		defer f.Close()
-		files = append(files, f)
+		files = append(files, bytes.NewBuffer(b))
 	}
 
 	var headCode bytes.Buffer