diff --git a/btest b/btest
index d63c410..1799bb4 100755
--- a/btest
+++ b/btest
@@ -1188,7 +1188,7 @@ class Test:
                 error(f"cannot write test's additional file '{fname}'")
 
             for line in lines:
-                ffile.write(line)
+                ffile.write(line.replace("\r\n", "\n"))
 
             ffile.close()
 
diff --git a/btest-bg-wait b/btest-bg-wait
index e8437af..ed06a00 100755
--- a/btest-bg-wait
+++ b/btest-bg-wait
@@ -85,7 +85,11 @@ function kill_procs {
 }
 
 function collect_output {
-    rm -f .stdout .stderr
+    # Truncate rather than rm: on Windows the parent process (btest)
+    # still holds these files open and rm would fail with EBUSY.
+    # Truncation is allowed because btest opens them with write-sharing.
+    : >.stdout
+    : >.stderr
 
     if [ $timeout_ok != 1 ] && [ -s .timeout ]; then
         {