# PIC: Watchdog timer off by a factor of 4

I have a PIC16 (datasheet here) for which I use the watchdog timer. I configure the watchdog timer as follows:

WDTCONbits.WDTPS = 0b01110;

According to page 105 of the datasheet, this should configure the watchdog timer for 16 seconds. However, the timer interrupt is called after only 4 seconds. (I have tested the timer with other values and the 4x discrepancy always persists.)

My first thought was that it was due to the 4xPLL being enabled. But as far as I understand, the watchdog timer is based upon the LFINTOSC clock, which is invariant under the 4xPLL.

Why is my watchdog timer running at four times the speed it should be?