diff --git a/libc/upstream-netbsd/netbsd-compat.h b/libc/upstream-netbsd/netbsd-compat.h
new file mode 100644
index 0000000..a52052a
--- /dev/null
+++ b/libc/upstream-netbsd/netbsd-compat.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _BIONIC_NETBSD_COMPAT_H_included
+#define _BIONIC_NETBSD_COMPAT_H_included
+
+// NetBSD uses _DIAGASSERT to null-check arguments and the like.
+#include <assert.h>
+#define _DIAGASSERT(e) ((e) ? (void) 0 : __assert2(__FILE__, __LINE__, __func__, #e))
+
+#endif