diff --git a/src/basic/iovec-util.h b/src/basic/iovec-util.h
index bc7a67054a..8cfa5717dc 100644
--- a/src/basic/iovec-util.h
+++ b/src/basic/iovec-util.h
@@ -8,6 +8,12 @@
 #include "alloc-util.h"
 #include "macro.h"
 
+/* An iovec pointing to a single NUL byte */
+#define IOVEC_NUL_BYTE (const struct iovec) {                   \
+                .iov_base = (void*) (const uint8_t[1]) { 0 },   \
+                .iov_len = 1,                                   \
+        }
+
 size_t iovec_total_size(const struct iovec *iovec, size_t n);
 
 bool iovec_increment(struct iovec *iovec, size_t n, size_t k);