diff --git a/ffmpeg/ffmpeg.go b/ffmpeg/ffmpeg.go
index 2187d89..497ee98 100644
--- a/ffmpeg/ffmpeg.go
+++ b/ffmpeg/ffmpeg.go
@@ -132,6 +132,9 @@ func (av *AVContext) SeekPosition(f float64) error {
 
 // SeekDuration seeks to keyframe before the  specified duration
 func (av *AVContext) SeekDuration(ts time.Duration) error {
+	if av.formatContext == nil || av.codecContext == nil {
+		return ErrDecoderNotFound
+	}
 	return seekDuration(av, ts)
 }
 
diff --git a/processor_test.go b/processor_test.go
index 9b45767..3bb3fb5 100644
--- a/processor_test.go
+++ b/processor_test.go
@@ -64,6 +64,7 @@ func TestProcessor(t *testing.T) {
 	}, WithDebug(true), WithLogger(zap.NewExample()))
 	doGoldenTests(t, filepath.Join(testDataDir, "golden/result-fallback-image"), []test{
 		{name: "corrupted with fallback image", path: "fit-in/100x100/corrupt/everybody-betray-me.mkv", expectCode: 406},
+		{name: "corrupted with fallback image", path: "filters:seek(0.1)/no_cover.mp3", expectCode: 406},
 	}, WithDebug(false), WithLogger(zap.NewExample()), WithFallbackImage("demo.png"))
 }
 
diff --git a/testdata/golden/result-fallback-image/filters%3Aseek%280.1%29/no_cover.mp3 b/testdata/golden/result-fallback-image/filters%3Aseek%280.1%29/no_cover.mp3
new file mode 100644
index 0000000..8c74ba6
--- /dev/null
+++ b/testdata/golden/result-fallback-image/filters%3Aseek%280.1%29/no_cover.mp3
@@ -0,0 +1 @@
+{"message":"ffmpeg: decoder not found","status":406}
\ No newline at end of file