diff --git a/go/cli/mcap/cmd/sort.go b/go/cli/mcap/cmd/sort.go
index e14df3a2bc..e7dacfda2e 100644
--- a/go/cli/mcap/cmd/sort.go
+++ b/go/cli/mcap/cmd/sort.go
@@ -123,7 +123,7 @@ func sortFile(w io.Writer, r io.ReadSeeker) error {
 		return fmt.Errorf("failed to read messages: %w", err)
 	}
 	schemas := make(map[uint16]*mcap.Schema)
-	channels := make(map[uint16]*mcap.Schema)
+	channels := make(map[uint16]*mcap.Channel)
 	message := mcap.Message{}
 	for {
 		schema, channel, _, err := it.NextInto(&message)
@@ -138,6 +138,7 @@ func sortFile(w io.Writer, r io.ReadSeeker) error {
 				if err != nil {
 					return fmt.Errorf("failed to write schema: %w", err)
 				}
+				schemas[schema.ID] = schema
 			}
 		}
 		if _, ok := channels[channel.ID]; !ok {
@@ -145,6 +146,7 @@ func sortFile(w io.Writer, r io.ReadSeeker) error {
 			if err != nil {
 				return fmt.Errorf("failed to write channel: %w", err)
 			}
+			channels[channel.ID] = channel
 		}
 		err = writer.WriteMessage(&message)
 		if err != nil {
diff --git a/go/cli/mcap/cmd/sort_test.go b/go/cli/mcap/cmd/sort_test.go
index ee7d0e5c03..3530726771 100644
--- a/go/cli/mcap/cmd/sort_test.go
+++ b/go/cli/mcap/cmd/sort_test.go
@@ -2,6 +2,8 @@ package cmd
 
 import (
 	"bytes"
+	"errors"
+	"io"
 	"testing"
 
 	"github.com/foxglove/mcap/go/mcap"
@@ -62,14 +64,32 @@ func TestSortFile(t *testing.T) {
 	w := &bytes.Buffer{}
 	require.NoError(t, sortFile(w, reader))
 
-	// verify it is now sorted
-	r, err := mcap.NewReader(bytes.NewReader(w.Bytes()))
+	lexer, err := mcap.NewLexer(bytes.NewReader(w.Bytes()))
 	require.NoError(t, err)
-
-	it, err := r.Messages(mcap.UsingIndex(false))
-	require.NoError(t, err)
-
-	_, _, msg, err := it.NextInto(nil)
-	require.NoError(t, err)
-	assert.Equal(t, 25, int(msg.LogTime))
+	var schemaCount, channelCount, messageCount int
+	var lastMessageTime uint64
+top:
+	for {
+		token, record, err := lexer.Next(nil)
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		require.NoError(t, err)
+		switch token {
+		case mcap.TokenMessage:
+			messageCount++
+			message, err := mcap.ParseMessage(record)
+			require.NoError(t, err)
+			require.GreaterOrEqual(t, message.LogTime, lastMessageTime)
+			lastMessageTime = message.LogTime
+		case mcap.TokenSchema:
+			schemaCount++
+		case mcap.TokenChannel:
+			channelCount++
+		case mcap.TokenDataEnd:
+			break top
+		}
+	}
+	assert.Equal(t, 1, schemaCount, "incorrect schema count")
+	assert.Equal(t, 2, channelCount, "incorrect channel count")
 }