diff --git a/src/main.zig b/src/main.zig
index 0e99915..b51b55a 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -2320,7 +2320,7 @@ fn getBatteryPercentage(io: std.Io, battery_id: []const u8) !u8 {
         // battery_id is unused on FreeBSD; sysctl exposes a single aggregate value.
         // For multi-battery systems the MIB would be hw.acpi.battery.N.life,
         // but hw.acpi.battery.life is the standard single-battery interface.
-        var capacity: c_int = undefined;
+        var capacity: c_int = -1;
         var size: usize = @sizeOf(c_int);
 
         const ret = sysctl.sysctlbyname("hw.acpi.battery.life", &capacity, &size, null, 0);