diff --git a/drivers/hid/wacom.h b/drivers/hid/wacom.h
index 4a7f8d363220..203d27d198b8 100644
--- a/drivers/hid/wacom.h
+++ b/drivers/hid/wacom.h
@@ -202,6 +202,21 @@ static inline void wacom_schedule_work(struct wacom_wac *wacom_wac,
 	}
 }
 
+/*
+ * Convert a signed 32-bit integer to an unsigned n-bit integer. Undoes
+ * the normally-helpful work of 'hid_snto32' for fields that use signed
+ * ranges for questionable reasons.
+ */
+static inline __u32 wacom_s32tou(s32 value, __u8 n)
+{
+	switch (n) {
+	case 8:  return ((__u8)value);
+	case 16: return ((__u16)value);
+	case 32: return ((__u32)value);
+	}
+	return value & (1 << (n - 1)) ? value & (~(~0U << n)) : value;
+}
+
 extern const struct hid_device_id wacom_ids[];
 
 void wacom_wac_irq(struct wacom_wac *wacom_wac, size_t len);
diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 2b0a5b8ca6e6..ccb74529bc78 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2303,7 +2303,7 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 	case HID_DG_TOOLSERIALNUMBER:
 		if (value) {
 			wacom_wac->serial[0] = (wacom_wac->serial[0] & ~0xFFFFFFFFULL);
-			wacom_wac->serial[0] |= (__u32)value;
+			wacom_wac->serial[0] |= wacom_s32tou(value, field->report_size);
 		}
 		return;
 	case HID_DG_TWIST:
@@ -2319,15 +2319,17 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 		return;
 	case WACOM_HID_WD_SERIALHI:
 		if (value) {
+			__u32 raw_value = wacom_s32tou(value, field->report_size);
+
 			wacom_wac->serial[0] = (wacom_wac->serial[0] & 0xFFFFFFFF);
-			wacom_wac->serial[0] |= ((__u64)value) << 32;
+			wacom_wac->serial[0] |= ((__u64)raw_value) << 32;
 			/*
 			 * Non-USI EMR devices may contain additional tool type
 			 * information here. See WACOM_HID_WD_TOOLTYPE case for
 			 * more details.
 			 */
 			if (value >> 20 == 1) {
-				wacom_wac->id[0] |= value & 0xFFFFF;
+				wacom_wac->id[0] |= raw_value & 0xFFFFF;
 			}
 		}
 		return;
@@ -2339,7 +2341,7 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 		 * bitwise OR so the complete value can be built
 		 * up over time :(
 		 */
-		wacom_wac->id[0] |= value;
+		wacom_wac->id[0] |= wacom_s32tou(value, field->report_size);
 		return;
 	case WACOM_HID_WD_OFFSETLEFT:
 		if (features->offset_left && value != features->offset_left)