diff --git a/src/display/spectrogram.c b/src/display/spectrogram.c
index f74822e..9845fe8 100644
--- a/src/display/spectrogram.c
+++ b/src/display/spectrogram.c
@@ -41,6 +41,7 @@ void spectrogram_init(unsigned width, unsigned height, unsigned left, unsigned t
     sgam_left = left;
     sgam_top = top;
     smoothed_values = (double *)malloc(sizeof(double) * width);
+    memset(smoothed_values, 0, sizeof(double) * width);
 }
 
 void spectrogram_render_bg(fb_buf_t *fb)