diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h
index a9efa807b7..af272c2a80 100644
--- a/bsd-user/qemu.h
+++ b/bsd-user/qemu.h
@@ -462,6 +462,19 @@ static inline void *lock_user_string(abi_ulong guest_addr)
 #define unlock_user_struct(host_ptr, guest_addr, copy)          \
     unlock_user(host_ptr, guest_addr, (copy) ? sizeof(*host_ptr) : 0)
 
+static inline uint64_t target_arg64(uint32_t word0, uint32_t word1)
+{
+#if TARGET_ABI_BITS == 32
+#ifdef TARGET_WORDS_BIGENDIAN
+    return ((uint64_t)word0 << 32) | word1;
+#else
+    return ((uint64_t)word1 << 32) | word0;
+#endif
+#else /* TARGET_ABI_BITS != 32 */
+    return word0;
+#endif /* TARGET_ABI_BITS != 32 */
+}
+
 #include <pthread.h>
 
 #include "user/safe-syscall.h"