diff --git a/server/char-device.c b/server/char-device.c
index d3259320..16687d83 100644
--- a/server/char-device.c
+++ b/server/char-device.c
@@ -31,6 +31,9 @@
 #define RED_CHAR_DEVICE_WAIT_TOKENS_TIMEOUT 30000
 #define MAX_POOL_SIZE (10 * 64 * 1024)
 
+struct RedCharDeviceWriteBufferPrivate {
+};
+
 typedef struct RedCharDeviceClient RedCharDeviceClient;
 struct RedCharDeviceClient {
     RedCharDevice *dev;
@@ -539,7 +542,13 @@ static RedCharDeviceWriteBuffer *__red_char_device_write_buffer_get(
     if (ret) {
         dev->priv->cur_pool_size -= ret->buf_size;
     } else {
-        ret = spice_new0(RedCharDeviceWriteBuffer, 1);
+        struct RedCharDeviceWriteBufferFull {
+            RedCharDeviceWriteBuffer buffer;
+            RedCharDeviceWriteBufferPrivate priv;
+        } *write_buf;
+        write_buf = spice_new0(struct RedCharDeviceWriteBufferFull, 1);
+        ret = &write_buf->buffer;
+        ret->priv = &write_buf->priv;
     }
 
     spice_assert(!ret->buf_used);
diff --git a/server/char-device.h b/server/char-device.h
index 7854086c..9bfd7c65 100644
--- a/server/char-device.h
+++ b/server/char-device.h
@@ -146,6 +146,7 @@ GType red_char_device_get_type(void) G_GNUC_CONST;
  * */
 
 /* buffer that is used for writing to the device */
+typedef struct RedCharDeviceWriteBufferPrivate RedCharDeviceWriteBufferPrivate;
 typedef struct RedCharDeviceWriteBuffer {
     int origin;
     RedClient *client; /* The client that sent the message to the device.
@@ -156,6 +157,8 @@ typedef struct RedCharDeviceWriteBuffer {
     uint32_t buf_used;
     uint32_t token_price;
     uint32_t refs;
+
+    RedCharDeviceWriteBufferPrivate *priv;
 } RedCharDeviceWriteBuffer;
 
 void red_char_device_reset_dev_instance(RedCharDevice *dev,