diff --git a/storage/innobase/include/os0file.h b/storage/innobase/include/os0file.h
index c0bcae941fd..f6a3ae2224b 100644
--- a/storage/innobase/include/os0file.h
+++ b/storage/innobase/include/os0file.h
@@ -1350,6 +1350,12 @@ struct os_aio_userdata_t
   fil_node_t* node;
   IORequest type;
   void* message;
+
+  os_aio_userdata_t(fil_node_t*node, IORequest type, void*message) :
+    node(node), type(type), message(message) {}
+
+  /** Construct from tpool::aiocb::m_userdata[] */
+  os_aio_userdata_t(const char *buf) { memcpy((void*)this, buf, sizeof*this); }
 };
 /**
 NOTE! Use the corresponding macro os_aio(), not directly this function!
diff --git a/storage/innobase/os/os0file.cc b/storage/innobase/os/os0file.cc
index 02040da9e52..096bbd8ff0b 100644
--- a/storage/innobase/os/os0file.cc
+++ b/storage/innobase/os/os0file.cc
@@ -3883,7 +3883,7 @@ extern void fil_aio_callback(os_aio_userdata_t *data);
 static void io_callback(tpool::aiocb* cb)
 {
 	ut_a(cb->m_err == DB_SUCCESS);
-	os_aio_userdata_t data = *(os_aio_userdata_t*)cb->m_userdata;
+	os_aio_userdata_t data(cb->m_userdata);
 	/* Return cb back to cache*/
 	if (cb->m_opcode == tpool::aio_opcode::AIO_PREAD) {
 		if (read_slots->contains(cb)) {
diff --git a/tpool/tpool.h b/tpool/tpool.h
index 403a7faba50..ae9baf236b0 100644
--- a/tpool/tpool.h
+++ b/tpool/tpool.h
@@ -137,7 +137,7 @@ struct aiocb
   int m_err;
   void *m_internal;
   task m_internal_task;
-  char m_userdata[MAX_AIO_USERDATA_LEN];
+  alignas(8) char m_userdata[MAX_AIO_USERDATA_LEN];
 
   aiocb() : m_internal_task(nullptr, nullptr)
   {}