diff --git a/noisicaa/builtin_nodes/step_sequencer/processor.h b/noisicaa/builtin_nodes/step_sequencer/processor.h
index c0f17a9c..56d7eb8e 100644
--- a/noisicaa/builtin_nodes/step_sequencer/processor.h
+++ b/noisicaa/builtin_nodes/step_sequencer/processor.h
@@ -38,8 +38,6 @@ namespace noisicaa {
 using namespace std;
 
 class HostSystem;
-class CSoundUtil;
-class FluidSynthUtil;
 
 namespace pb {
 class StepSequencerSpec;