diff --git a/src/libnm-core-impl/tests/test-general.c b/src/libnm-core-impl/tests/test-general.c
index 485264fa1f..0603ea61e8 100644
--- a/src/libnm-core-impl/tests/test-general.c
+++ b/src/libnm-core-impl/tests/test-general.c
@@ -557,6 +557,21 @@ test_nm_hash(void)
 #endif
 
     NM_STATIC_ASSERT_EXPR_VOID(NM_HASH_COMBINE_BOOLS(int, 1, 0, 1) == 5);
+
+    g_assert_cmpmem(NM_HASH_SEED_16(55, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15),
+                    16,
+                    ((guint8[16]){55, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}),
+                    16);
+
+    g_assert_cmpmem(NM_HASH_SEED_16_U64(1), 16, ((guint8[16]){0, 0, 0, 0, 0, 0, 0, 1, 0}), 16);
+    g_assert_cmpmem(NM_HASH_SEED_16_U64(0x1234567890ABCDEFu),
+                    16,
+                    ((guint8[16]){0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF, 0}),
+                    16);
+
+    g_assert_cmpint(c_siphash_hash(NM_HASH_SEED_16_U64(0x780E21E45489CC6Fu), (guint8 *) "foo", 3),
+                    ==,
+                    0XA5A41E5C1B4153BFu);
 }
 
 /*****************************************************************************/
diff --git a/src/libnm-glib-aux/nm-hash-utils.h b/src/libnm-glib-aux/nm-hash-utils.h
index c1306200b4..5a17af5bdb 100644
--- a/src/libnm-glib-aux/nm-hash-utils.h
+++ b/src/libnm-glib-aux/nm-hash-utils.h
@@ -14,6 +14,30 @@
 #define NM_HASH_SEED_16(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, aa, ab, ac, ad, ae, af) \
     ((const guint8[16]){a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, aa, ab, ac, ad, ae, af})
 
+struct _nm_packed _nm_hash_seed_16_u64_data {
+    guint64 s1;
+    guint64 s2;
+};
+
+G_STATIC_ASSERT(sizeof(struct _nm_hash_seed_16_u64_data) == 16);
+G_STATIC_ASSERT(sizeof(struct _nm_hash_seed_16_u64_data) == sizeof(guint64) * 2);
+
+/* c_siphash_init() has a seed of 16 bytes (NM_HASH_SEED_16()). That is
+ * cumbersome to use, because we usually just hardcode an arbitrarily chosen,
+ * fixed number.
+ *
+ * This macro takes a u64 (in host-endianness) and returns a 16 byte seed
+ * buffer. The number will be big endian encoded, to be architecture
+ * independent. */
+#define NM_HASH_SEED_16_U64(u64)                              \
+    ((const guint8 *) ((gpointer)                             \
+                       & ((struct _nm_hash_seed_16_u64_data){ \
+                           .s1 = htobe64((u64)),              \
+                           .s2 = 0,                           \
+                       })))
+
+/*****************************************************************************/
+
 void nm_hash_siphash42_init(CSipHash *h, guint static_seed);
 
 /* Siphash24 of binary buffer @arr and @len, using the randomized seed from
@@ -22,7 +46,7 @@ void nm_hash_siphash42_init(CSipHash *h, guint static_seed);
  * Note, that this is guaranteed to use siphash42 under the hood (contrary to
  * all other NMHash API, which leave this undefined). That matters at the point,
  * where the caller needs to be sure that a reasonably strong hashing algorithm
- * is used.  (Yes, NMHash is all about siphash24, but otherwise that is not promised
+ * is used.  (Yes, NMHash is all about siphash42, but otherwise that is not promised
  * anywhere).
  *
  * Another difference is, that this returns guint64 (not guint like other NMHash functions).