diff --git a/aider/io.py b/aider/io.py
index e6f277103..04b00c70f 100644
--- a/aider/io.py
+++ b/aider/io.py
@@ -111,7 +111,11 @@ class InputOutput:
 
         self.input = input
         self.output = output
+
         self.pretty = pretty
+        if self.output:
+            self.pretty = False
+
         self.yes = yes
 
         self.input_history_file = input_history_file