diff --git a/internal/imgcache/processor_test.go b/internal/imgcache/processor_test.go
index 50fa026..c4a036b 100644
--- a/internal/imgcache/processor_test.go
+++ b/internal/imgcache/processor_test.go
@@ -3,7 +3,6 @@ package imgcache
 import (
 	"bytes"
 	"context"
-	"errors"
 	"image"
 	"image/color"
 	"image/jpeg"
@@ -457,7 +456,7 @@ func TestImageProcessor_DecodeAVIF(t *testing.T) {
 	}
 }
 
-func TestImageProcessor_RejectsUnsupportedOutputFormat_AVIF(t *testing.T) {
+func TestImageProcessor_EncodeAVIF(t *testing.T) {
 	proc := NewImageProcessor()
 	ctx := context.Background()
 
@@ -470,12 +469,32 @@ func TestImageProcessor_RejectsUnsupportedOutputFormat_AVIF(t *testing.T) {
 		FitMode: FitCover,
 	}
 
-	_, err := proc.Process(ctx, bytes.NewReader(input), req)
-	if err == nil {
-		t.Fatal("Process() should return error for unsupported AVIF encoding")
+	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	if err != nil {
+		t.Fatalf("Process() error = %v, want nil (AVIF encoding should work)", err)
+	}
+	defer result.Content.Close()
+
+	// Verify output is valid AVIF
+	data, err := io.ReadAll(result.Content)
+	if err != nil {
+		t.Fatalf("failed to read result: %v", err)
 	}
 
-	if !errors.Is(err, ErrUnsupportedOutputFormat) {
-		t.Errorf("Process() error = %v, want ErrUnsupportedOutputFormat", err)
+	mime, err := DetectFormat(data)
+	if err != nil {
+		t.Fatalf("DetectFormat() error = %v", err)
+	}
+
+	if mime != MIMETypeAVIF {
+		t.Errorf("Output format = %v, want %v", mime, MIMETypeAVIF)
+	}
+
+	// Verify dimensions
+	if result.Width != 100 {
+		t.Errorf("Width = %d, want 100", result.Width)
+	}
+	if result.Height != 75 {
+		t.Errorf("Height = %d, want 75", result.Height)
 	}
 }