diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index bd54c0834..0f06c30a9 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -692,9 +692,12 @@ class Coder:
             return
 
     def get_input(self):
+        inchat_files = self.get_inchat_relative_files()
+        read_only_files = [self.get_rel_fname(fname) for fname in self.abs_read_only_fnames]
+        all_files = sorted(set(inchat_files + read_only_files))
         return self.io.get_input(
             self.root,
-            self.get_inchat_relative_files(),
+            all_files,
             self.get_addable_relative_files(),
             self.commands,
             self.abs_read_only_fnames,