diff --git a/internal/cuetxtar/txtar.go b/internal/cuetxtar/txtar.go
index ba818719747..7848df64701 100644
--- a/internal/cuetxtar/txtar.go
+++ b/internal/cuetxtar/txtar.go
@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"maps"
 	"os"
 	"path"
 	"path/filepath"
@@ -418,13 +419,6 @@ func (x *TxTarTest) run(t *testing.T, f func(tc *Test)) {
 				t.Fatalf("error parsing txtar file: %v", err)
 			}
 
-			// Record ordering of files in the archive to preserve that ordering
-			// later.
-			ordering := map[string]int{}
-			for i, f := range a.Files {
-				ordering[f.Name] = i
-			}
-
 			tc := &Test{
 				T:       t,
 				Archive: a,
@@ -487,6 +481,10 @@ func (x *TxTarTest) run(t *testing.T, f func(tc *Test)) {
 				index[f.Name] = i
 			}
 
+			// Record ordering of files in the archive to preserve that ordering
+			// later.
+			ordering := maps.Clone(index)
+
 			// Add diff files between fallback and main file. These are added
 			// as regular output files so that they can be updated as well.
 			for _, sub := range tc.outFiles {
@@ -494,6 +492,9 @@ func (x *TxTarTest) run(t *testing.T, f func(tc *Test)) {
 					continue
 				}
 				if j, ok := index[sub.fallback]; ok {
+					if _, ok := ordering[sub.name]; !ok {
+						ordering[sub.name] = j
+					}
 					fallback := a.Files[j].Data
 
 					result := sub.buf.Bytes()
@@ -502,6 +503,9 @@ func (x *TxTarTest) run(t *testing.T, f func(tc *Test)) {
 					}
 
 					diffName := "diff/-" + sub.name + "<==>+" + sub.fallback
+					if _, ok := ordering[diffName]; !ok {
+						ordering[diffName] = j
+					}
 					switch diff := diff.Diff("old", fallback, "new", result); {
 					case len(diff) > 0:
 						tc.outFiles = append(tc.outFiles, file{
@@ -540,27 +544,7 @@ func (x *TxTarTest) run(t *testing.T, f func(tc *Test)) {
 				}
 			}
 
-			// Insert results of this test at first location of any existing
-			// test or at end of list otherwise.
-			k := len(a.Files)
-			for _, sub := range tc.outFiles {
-				if i, ok := index[sub.name]; ok {
-					k = i
-					break
-				}
-				if i, ok := index[sub.fallback]; ok {
-					k = i
-					break
-				}
-			}
-
-			// Filter files up to k from the original list.
 			files := make([]txtar.File, 0, len(a.Files))
-			for _, f := range a.Files[:k] {
-				if _, ok := index[f.Name]; ok {
-					files = append(files, f)
-				}
-			}
 
 			for _, sub := range tc.outFiles {
 				result := sub.buf.Bytes()
@@ -607,7 +591,7 @@ func (x *TxTarTest) run(t *testing.T, f func(tc *Test)) {
 
 			// Add remaining unrelated files, ignoring files that were already
 			// added.
-			for _, f := range a.Files[k:] {
+			for _, f := range a.Files {
 				if _, ok := index[f.Name]; ok {
 					files = append(files, f)
 				}