diff --git a/client/hostinfo_unix.C b/client/hostinfo_unix.C
index 974df61945..0f63182347 100644
--- a/client/hostinfo_unix.C
+++ b/client/hostinfo_unix.C
@@ -121,7 +121,7 @@ bool HOST_INFO::host_is_running_on_batteries() {
     if (fapm) {          // Then we're using APM!  Yay.
         // Supposedly we're on batteries if the 5th entry is zero.
         //
-        fscanf(f, "%10s %d.%d %x %x",
+        fscanf(fapm, "%10s %d.%d %x %x",
             apm_driver_version,
             &apm_major_version,
             &apm_minor_version,