1 files changed, 2 insertions, 1 deletions
diff --git a/unsupported/Battery.c b/unsupported/Battery.c
index 080cf540..121d2e49 100644
--- a/unsupported/Battery.c
+++ b/unsupported/Battery.c
@@ -1,7 +1,8 @@
+#include <math.h>
 
 #include "BatteryMeter.h"
 
 void Battery_getData(double* level, ACPresence* isOnAC) {
-   *level = -1;
+   *level = NAN;
    *isOnAC = AC_ERROR;
 }