diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index 03a246e60fd9..21c4c34c52d8 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -63,7 +63,7 @@ static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
 	spin_unlock_irqrestore(&queue->lock, flags);
 }
 
-s32 scaled_ppm_to_ppb(long ppm)
+long scaled_ppm_to_ppb(long ppm)
 {
 	/*
 	 * The 'freq' field in the 'struct timex' is in parts per
@@ -80,7 +80,7 @@ s32 scaled_ppm_to_ppb(long ppm)
 	s64 ppb = 1 + ppm;
 	ppb *= 125;
 	ppb >>= 13;
-	return (s32) ppb;
+	return (long) ppb;
 }
 EXPORT_SYMBOL(scaled_ppm_to_ppb);
 
@@ -138,7 +138,7 @@ static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
 		delta = ktime_to_ns(kt);
 		err = ops->adjtime(ops, delta);
 	} else if (tx->modes & ADJ_FREQUENCY) {
-		s32 ppb = scaled_ppm_to_ppb(tx->freq);
+		long ppb = scaled_ppm_to_ppb(tx->freq);
 		if (ppb > ops->max_adj || ppb < -ops->max_adj)
 			return -ERANGE;
 		if (ops->adjfine)
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index d3e8ba5c7125..6d6b42143eff 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -222,7 +222,7 @@ extern int ptp_clock_index(struct ptp_clock *ptp);
  * @ppm:    Parts per million, but with a 16 bit binary fractional field
  */
 
-extern s32 scaled_ppm_to_ppb(long ppm);
+extern long scaled_ppm_to_ppb(long ppm);
 
 /**
  * ptp_find_pin() - obtain the pin index of a given auxiliary function