diff --git a/misoclib/tools/litescope/host/driver/reg.py b/misoclib/tools/litescope/host/driver/reg.py
index c101e23c7..204a6262b 100644
--- a/misoclib/tools/litescope/host/driver/reg.py
+++ b/misoclib/tools/litescope/host/driver/reg.py
@@ -20,7 +20,7 @@ class MappedReg:
             data = 0
             for i in range(self.length):
                 data = data << self.busword
-                data |= read_datas[i]
+                data |= datas[i]
             return data
  
     def write(self, value):