diff --git a/src/monitor/scopes/monitoraudiolevel.cpp b/src/monitor/scopes/monitoraudiolevel.cpp
--- a/src/monitor/scopes/monitoraudiolevel.cpp
+++ b/src/monitor/scopes/monitoraudiolevel.cpp
@@ -30,6 +30,7 @@
 #include <QVBoxLayout>
 #include <QFont>
 #include <QDebug>
+#include <math.h>
 
 const double log_factor = 1.0 / log10(1.0/127);