diff --git a/libc/upstream-openbsd/arith.h b/libc/upstream-openbsd/arith.h
new file mode 100644
index 0000000..c57ce12
--- /dev/null
+++ b/libc/upstream-openbsd/arith.h
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#define IEEE_8087
+#define Arith_Kind_ASL 1
+
+#if __LP64__
+#define Long int
+#define Intcast (int)(long)
+#define Double_Align
+#define X64_bit_pointers
+#endif
+
+#define INFNAN_CHECK
+#define MULTIPLE_THREADS