diff --git a/plugins/wacom-raw/fu-wacom-aes-device.c b/plugins/wacom-raw/fu-wacom-aes-device.c
index 393873751..c560e9c34 100644
--- a/plugins/wacom-raw/fu-wacom-aes-device.c
+++ b/plugins/wacom-raw/fu-wacom-aes-device.c
@@ -175,10 +175,10 @@ fu_wacom_aes_device_write_block (FuWacomAesDevice *self,
 				 guint32 idx,
 				 guint32 address,
 				 const guint8 *data,
-				 guint16 datasz,
+				 gsize datasz,
 				 GError **error)
 {
-	guint blocksz = fu_wacom_device_get_block_sz (FU_WACOM_DEVICE (self));
+	gsize blocksz = fu_wacom_device_get_block_sz (FU_WACOM_DEVICE (self));
 	FuWacomRawRequest req = {
 		.cmd = FU_WACOM_RAW_BL_CMD_WRITE_FLASH,
 		.echo = (guint8) idx + 1,
@@ -194,7 +194,7 @@ fu_wacom_aes_device_write_block (FuWacomAesDevice *self,
 			     G_IO_ERROR,
 			     G_IO_ERROR_FAILED,
 			     "block size 0x%x != 0x%x untested",
-			     datasz, (guint) blocksz);
+			     (guint) datasz, (guint) blocksz);
 		return FALSE;
 	}
 	memcpy (&req.data, data, datasz);
diff --git a/plugins/wacom-raw/fu-wacom-device.c b/plugins/wacom-raw/fu-wacom-device.c
index 359fba832..309b8b6cc 100644
--- a/plugins/wacom-raw/fu-wacom-device.c
+++ b/plugins/wacom-raw/fu-wacom-device.c
@@ -39,7 +39,7 @@ fu_wacom_device_to_string (FuDevice *device, guint idt, GString *str)
 	fu_common_string_append_kx (str, idt, "FlashSize", priv->flash_size);
 }
 
-guint
+gsize
 fu_wacom_device_get_block_sz (FuWacomDevice *self)
 {
 	FuWacomDevicePrivate *priv = GET_PRIVATE (self);
diff --git a/plugins/wacom-raw/fu-wacom-device.h b/plugins/wacom-raw/fu-wacom-device.h
index f466407cb..d4c6dbf17 100644
--- a/plugins/wacom-raw/fu-wacom-device.h
+++ b/plugins/wacom-raw/fu-wacom-device.h
@@ -44,5 +44,5 @@ gboolean	 fu_wacom_device_erase_all	(FuWacomDevice	*self,
 						 GError		**error);
 gboolean	 fu_wacom_device_check_mpu	(FuWacomDevice	*self,
 						 GError		**error);
-guint		 fu_wacom_device_get_block_sz	(FuWacomDevice	*self);
+gsize		 fu_wacom_device_get_block_sz	(FuWacomDevice	*self);
 guint		 fu_wacom_device_get_base_addr	(FuWacomDevice	*self);
diff --git a/plugins/wacom-raw/fu-wacom-emr-device.c b/plugins/wacom-raw/fu-wacom-emr-device.c
index 0abbb5ac3..c42c1a0a0 100644
--- a/plugins/wacom-raw/fu-wacom-emr-device.c
+++ b/plugins/wacom-raw/fu-wacom-emr-device.c
@@ -136,10 +136,10 @@ fu_wacom_emr_device_write_block (FuWacomEmrDevice *self,
 				 guint32 idx,
 				 guint32 address,
 				 const guint8 *data,
-				 guint16 datasz,
+				 gsize datasz,
 				 GError **error)
 {
-	guint blocksz = fu_wacom_device_get_block_sz (FU_WACOM_DEVICE (self));
+	gsize blocksz = fu_wacom_device_get_block_sz (FU_WACOM_DEVICE (self));
 	FuWacomRawRequest req = {
 		.cmd = FU_WACOM_RAW_BL_CMD_WRITE_FLASH,
 		.echo = (guint8) idx + 1,
@@ -155,7 +155,7 @@ fu_wacom_emr_device_write_block (FuWacomEmrDevice *self,
 			     G_IO_ERROR,
 			     G_IO_ERROR_FAILED,
 			     "data size 0x%x too large for packet",
-			     datasz);
+			     (guint) datasz);
 		return FALSE;
 	}
 	if (datasz != blocksz) {
@@ -163,7 +163,7 @@ fu_wacom_emr_device_write_block (FuWacomEmrDevice *self,
 			     G_IO_ERROR,
 			     G_IO_ERROR_FAILED,
 			     "block size 0x%x != 0x%x untested",
-			     datasz, (guint) blocksz);
+			     (guint) datasz, (guint) blocksz);
 		return FALSE;
 	}