--- a/setupsrc/base.py	2026-03-10 23:18:27.497899682 +0100
+++ b/setupsrc/base.py	2026-03-10 23:19:24.051760735 +0100
@@ -640,6 +640,8 @@
         if stderr is not None:
             # allow the caller to pass e.g. subprocess.STDOUT
             kwargs["stderr"] = stderr
+    else:
+        kwargs["capture_output"] = True
     
     comp_process = subprocess.run(command, cwd=cwd, check=check, **kwargs)
     if capture: