diff --git a/testsuite/grep/grep-handles-binary-files b/testsuite/grep/grep-handles-binary-files
index 2679add6d..edb2042e7 100644
--- a/testsuite/grep/grep-handles-binary-files
+++ b/testsuite/grep/grep-handles-binary-files
@@ -1,2 +1 @@
-echo -e '\0foo' >foo
-busybox grep foo foo
+echo -e '\0foo' | busybox grep foo
diff --git a/testsuite/grep/grep-matches-NUL b/testsuite/grep/grep-matches-NUL
index 04c7fd3f5..597d22cb4 100644
--- a/testsuite/grep/grep-matches-NUL
+++ b/testsuite/grep/grep-matches-NUL
@@ -1,3 +1,2 @@
 # XFAIL
-echo -e '\0' >foo
-busybox grep . foo
+echo -e '\0' | busybox grep .