diff --git a/plugins/zynaddsubfx/src/Synth/ADnote.cpp b/plugins/zynaddsubfx/src/Synth/ADnote.cpp
index 5a6499d43..20ee83a19 100644
--- a/plugins/zynaddsubfx/src/Synth/ADnote.cpp
+++ b/plugins/zynaddsubfx/src/Synth/ADnote.cpp
@@ -788,7 +788,8 @@ void ADnote::compute_unison_freq_rap(int nvoice){
 			pos=1.0;
 			step=-step;
 		};
-		unison_freq_rap[nvoice][k]=1.0+((unison_base_freq_rap[nvoice][k]-1.0)+pos*unison_vibratto[nvoice].amplitude)*relbw;
+		REALTYPE vibratto_val=pos-0.3*pos*pos*pos;//make the vibratto lfo smoother
+		unison_freq_rap[nvoice][k]=1.0+((unison_base_freq_rap[nvoice][k]-1.0)+vibratto_val*unison_vibratto[nvoice].amplitude)*relbw;
 		
 		unison_vibratto[nvoice].position[k]=pos;
 		step=unison_vibratto[nvoice].step[k]=step;