diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 595bc2ac1..b712d00ed 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -245,6 +245,8 @@ class Coder:
         self.verbose = verbose
         self.abs_fnames = set()
         self.abs_read_only_fnames = set()
+        if read_only_fnames:
+            self.abs_read_only_fnames = set(self.abs_root_path(fname) for fname in read_only_fnames)
 
         if cur_messages:
             self.cur_messages = cur_messages