diff --git a/src/basic/socket-util.h b/src/basic/socket-util.h
index 7d504319a8..00c2998adb 100644
--- a/src/basic/socket-util.h
+++ b/src/basic/socket-util.h
@@ -183,7 +183,7 @@ int flush_accept(int fd);
  * riscv32. */
 #define CMSG_TYPED_DATA(cmsg, type)                                     \
         ({                                                              \
-                struct cmsghdr *_cmsg = cmsg;                           \
+                struct cmsghdr *_cmsg = (cmsg);                         \
                 assert_cc(__alignof__(type) <= __alignof__(struct cmsghdr)); \
                 _cmsg ? CAST_ALIGN_PTR(type, CMSG_DATA(_cmsg)) : (type*) NULL; \
         })