diff --git a/effect_stereo_panorama.cpp b/effect_stereo_panorama.cpp
index 869a8a3..afeb298 100644
--- a/effect_stereo_panorama.cpp
+++ b/effect_stereo_panorama.cpp
@@ -69,7 +69,7 @@ inline float mapfloat(float val, float in_min, float in_max, float out_min, floa
 void AudioEffectStereoPanorama::panorama(float p)
 {
   pan_r = mapfloat(p, 0.0, 1.0, -1.0, 1.0);
-  pan_l = pan_r * -1.0;
+  pan_l = mapfloat(p, 0.0, 1.0, 1.0, -1.0);
 }
 
 void AudioEffectStereoPanorama::update(void)