diff --git a/target/linux/ramips/mt7621/config-3.18 b/target/linux/ramips/mt7621/config-3.18
index 7168997159..fb05d1e645 100644
--- a/target/linux/ramips/mt7621/config-3.18
+++ b/target/linux/ramips/mt7621/config-3.18
@@ -173,6 +173,7 @@ CONFIG_RCU_STALL_COMMON=y
 CONFIG_RESET_CONTROLLER=y
 CONFIG_RFS_ACCEL=y
 CONFIG_RPS=y
+CONFIG_RTC_CLASS=y
 CONFIG_SCHED_SMT=y
 # CONFIG_SCSI_DMA is not set
 CONFIG_SERIAL_8250_NR_UARTS=4