diff --git a/tests/spec/preprocess_dos.sh b/tests/spec/preprocess_dos.sh
index a63a982d043b5847b333d4e556892393f97c8a7d..26b571be5e0e46e39d4e8b0e8e2cfed89a498586 100755
--- a/tests/spec/preprocess_dos.sh
+++ b/tests/spec/preprocess_dos.sh
@@ -1,3 +1,5 @@
 #!/bin/sh
 gcc -C -E -I. -o $3 $2
-$1 -q $3
+# Note: some versions of dos2unix (e.g. Busybox) do not have a '-q' flag,
+# so we avoid using them
+$1 $3 >/dev/null 2>/dev/null