diff --git a/libc/upstream-openbsd/android/include/arith.h b/libc/upstream-openbsd/android/include/arith.h
index cb116d4..554aa85 100644
--- a/libc/upstream-openbsd/android/include/arith.h
+++ b/libc/upstream-openbsd/android/include/arith.h
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #define IEEE_8087
 
 #if defined(__LP64__)