diff --git a/pkg/document/block.go b/pkg/document/block.go
index 4dea384ee..bea7d5bab 100644
--- a/pkg/document/block.go
+++ b/pkg/document/block.go
@@ -3,6 +3,7 @@ package document
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"math"
 	"regexp"
 	"strconv"
@@ -47,7 +48,8 @@ type CodeBlockEncoding int
 const (
 	Fenced CodeBlockEncoding = iota + 1
 	UnfencedWithSpaces
-	UnfencedWithTab
+	// todo(sebastian): goldmark converts all tabs to spaces
+	// UnfencedWithTab
 )
 
 type CodeBlock struct {
@@ -69,23 +71,37 @@ var _ Block = (*CodeBlock)(nil)
 
 func newCodeBlock(
 	document *Document,
-	node *ast.FencedCodeBlock,
+	node ast.Node,
 	identityResolver identityResolver,
 	nameResolver *nameResolver,
 	source []byte,
-	encoding CodeBlockEncoding,
 	render renderer,
 ) (*CodeBlock, error) {
-	attributes, err := getAttributes(node, source, DefaultAttributeParser)
+	var fenced *ast.FencedCodeBlock
+	encoding := Fenced
+
+	switch node.Kind() {
+	case ast.KindCodeBlock:
+		// todo(sebastian): should we attempt to preserve tab vs spaces?
+		encoding = UnfencedWithSpaces
+		fenced = ast.NewFencedCodeBlock(ast.NewText())
+		fenced.BaseBlock = node.(*ast.CodeBlock).BaseBlock
+	case ast.KindFencedCodeBlock:
+		fenced = node.(*ast.FencedCodeBlock)
+	default:
+		return nil, errors.New("invalid node kind neither CodeBlock nor FencedCodeBlock")
+	}
+
+	attributes, err := getAttributes(fenced, source, DefaultAttributeParser)
 	if err != nil {
 		return nil, err
 	}
 
-	id, hasID := identityResolver.GetCellID(node, attributes)
+	id, hasID := identityResolver.GetCellID(fenced, attributes)
 
-	name, hasName := getName(node, source, nameResolver, attributes)
+	name, hasName := getName(fenced, source, nameResolver, attributes)
 
-	value, err := render(node, source)
+	value, err := render(fenced, source)
 	if err != nil {
 		return nil, err
 	}
@@ -96,16 +112,18 @@ func newCodeBlock(
 		encoding:      encoding,
 		id:            id,
 		idGenerated:   !hasID,
-		inner:         node,
-		intro:         getIntro(node, source),
-		language:      getLanguage(node, source),
-		lines:         getLines(node, source),
+		inner:         fenced,
+		intro:         getIntro(fenced, source),
+		language:      getLanguage(fenced, source),
+		lines:         getLines(fenced, source),
 		name:          name,
 		nameGenerated: !hasName,
 		value:         value,
 	}, nil
 }
 
+func (b *CodeBlock) FencedEncoding() bool { return b.encoding == Fenced }
+
 func (b *CodeBlock) Attributes() map[string]string { return b.attributes }
 
 func (b *CodeBlock) Background() bool {
diff --git a/pkg/document/document.go b/pkg/document/document.go
index 08ba4bef6..8f793cc84 100644
--- a/pkg/document/document.go
+++ b/pkg/document/document.go
@@ -3,7 +3,6 @@ package document
 import (
 	"bytes"
 	"fmt"
-	"strconv"
 	"sync"
 
 	"github.com/pkg/errors"
@@ -171,26 +170,16 @@ func (d *Document) parse() {
 
 func (d *Document) buildBlocksTree(parent ast.Node, node *Node) error {
 	for astNode := parent.FirstChild(); astNode != nil; astNode = astNode.NextSibling() {
-		codeBlockEncoding := Fenced
 		switch astNode.Kind() {
-		case ast.KindCodeBlock:
-			b := ast.NewFencedCodeBlock(ast.NewText())
-			b.BaseBlock = astNode.(*ast.CodeBlock).BaseBlock
-			astNode = b
-
-			codeBlockEncoding = UnfencedWithSpaces
-			fallthrough
-		case ast.KindFencedCodeBlock:
+		case ast.KindCodeBlock, ast.KindFencedCodeBlock:
 			block, err := newCodeBlock(
 				d,
-				astNode.(*ast.FencedCodeBlock),
+				astNode,
 				d.identityResolver,
 				d.nameResolver,
 				d.content,
-				codeBlockEncoding,
 				d.renderer,
 			)
-			block.attributes["runme.dev/fenced"] = strconv.FormatBool(codeBlockEncoding == Fenced)
 			if err != nil {
 				return errors.WithStack(err)
 			}
diff --git a/pkg/document/editor/cell.go b/pkg/document/editor/cell.go
index 29b509b5e..5e482054e 100644
--- a/pkg/document/editor/cell.go
+++ b/pkg/document/editor/cell.go
@@ -175,6 +175,10 @@ func toCellsRec(
 			}
 			metadata[PrefixAttributeName(InternalAttributePrefix, "nameGenerated")] = nameGeneratedStr
 
+			if !block.FencedEncoding() {
+				metadata[PrefixAttributeName(InternalAttributePrefix, "fenced")] = "false"
+			}
+
 			*cells = append(*cells, &Cell{
 				Kind:       CodeKind,
 				Value:      string(block.Content()),
@@ -322,7 +326,15 @@ func serializeCellCodeBlock(w io.Writer, cell *Cell) {
 	var buf bytes.Buffer
 	value := cell.Value
 
-	if b, _ := strconv.ParseBool(cell.Metadata[PrefixAttributeName(InternalAttributePrefix, "fenced")]); b {
+	if b, err := strconv.ParseBool(cell.Metadata[PrefixAttributeName(InternalAttributePrefix, "fenced")]); err == nil && !b {
+		for _, v := range strings.Split(value, "\n") {
+			_, _ = buf.Write(bytes.Repeat([]byte{' '}, 4))
+			_, _ = buf.WriteString(v)
+			_ = buf.WriteByte('\n')
+		}
+
+		serializeCellOutputsText(&buf, cell)
+	} else {
 		ticksCount := longestBacktickSeq(value)
 		if ticksCount < 3 {
 			ticksCount = 3
@@ -340,14 +352,6 @@ func serializeCellCodeBlock(w io.Writer, cell *Cell) {
 		serializeCellOutputsText(&buf, cell)
 
 		_, _ = buf.Write(bytes.Repeat([]byte{'`'}, ticksCount))
-	} else {
-		for _, v := range strings.Split(value, "\n") {
-			_, _ = buf.Write(bytes.Repeat([]byte{' '}, 4))
-			_, _ = buf.WriteString(v)
-			_ = buf.WriteByte('\n')
-		}
-
-		serializeCellOutputsText(&buf, cell)
 	}
 
 	serializeCellOutputsImage(&buf, cell)