diff --git a/cocotbext/axi/axi_master.py b/cocotbext/axi/axi_master.py
index c43d9a4..a6394d8 100644
--- a/cocotbext/axi/axi_master.py
+++ b/cocotbext/axi/axi_master.py
@@ -325,7 +325,7 @@ class AxiMasterWrite(Reset):
         self.in_flight_operations += 1
         self._idle.clear()
 
-        cmd = AxiWriteCmd(address, bytearray(data), awid, burst, size, lock,
+        cmd = AxiWriteCmd(address, bytes(data), awid, burst, size, lock,
             cache, prot, qos, region, user, wuser, event)
         self.write_command_queue.put_nowait(cmd)
 
diff --git a/cocotbext/axi/axil_master.py b/cocotbext/axi/axil_master.py
index a866647..b8082ff 100644
--- a/cocotbext/axi/axil_master.py
+++ b/cocotbext/axi/axil_master.py
@@ -153,7 +153,7 @@ class AxiLiteMasterWrite(Reset):
         self.in_flight_operations += 1
         self._idle.clear()
 
-        self.write_command_queue.put_nowait(AxiLiteWriteCmd(address, bytearray(data), prot, event))
+        self.write_command_queue.put_nowait(AxiLiteWriteCmd(address, bytes(data), prot, event))
 
         return event