diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
index 65d17781d..5ba2aaebe 100644
--- a/drivers/pps/clients/pps-gpio.c
+++ b/drivers/pps/clients/pps-gpio.c
@@ -156,6 +156,13 @@ get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
 				IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
 	}
 
+	/* The handler timestamps the pulse, so it has to run in hard-irq
+	 * context. Under PREEMPT_RT it would otherwise be force-threaded and
+	 * the timestamp taken after thread wakeup latency, adding microseconds
+	 * of jitter to an edge that should be good to nanoseconds.
+	 */
+	flags |= IRQF_NO_THREAD;
+
 	return flags;
 }