diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 9847aa823..df2813103 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -2065,5 +2065,6 @@ class Coder:
             "Add command output to the chat?", allow_never=True
         ):
             num_lines = len(accumulated_output.strip().splitlines())
-            self.io.tool_output(f"Added {num_lines} lines of output to the chat.")
+            line_plural = "line" if num_lines == 1 else "lines"
+            self.io.tool_output(f"Added {num_lines} {line_plural} of output to the chat.")
             return accumulated_output
diff --git a/aider/commands.py b/aider/commands.py
index e93046dd9..fc2d40e65 100644
--- a/aider/commands.py
+++ b/aider/commands.py
@@ -880,7 +880,8 @@ class Commands:
 
         if add:
             num_lines = len(combined_output.strip().splitlines())
-            self.io.tool_output(f"Added {num_lines} lines of output to the chat.")
+            line_plural = "line" if num_lines == 1 else "lines"
+            self.io.tool_output(f"Added {num_lines} {line_plural} of output to the chat.")
 
             msg = prompts.run_output.format(
                 command=args,