diff --git a/drivers/power/battery_charger.c b/drivers/power/battery_charger.c
index 5467f49093..70f707aa7b 100644
--- a/drivers/power/battery_charger.c
+++ b/drivers/power/battery_charger.c
@@ -285,6 +285,10 @@ int battery_charger_register(FAR const char *devpath,
 {
   int ret;
 
+  /* Initialize the semaphore */
+
+  nxsem_init(&dev->batsem, 0, 1);
+
   /* Register the character driver */
 
   ret = register_driver(devpath, &g_batteryops, 0555, dev);
diff --git a/drivers/power/battery_gauge.c b/drivers/power/battery_gauge.c
index 9936147be1..63b59092a9 100644
--- a/drivers/power/battery_gauge.c
+++ b/drivers/power/battery_gauge.c
@@ -248,6 +248,10 @@ int battery_gauge_register(FAR const char *devpath,
 {
   int ret;
 
+  /* Initialize the semaphore */
+
+  nxsem_init(&dev->batsem, 0, 1);
+
   /* Register the character driver */
 
   ret = register_driver(devpath, &g_batteryops, 0555, dev);