diff --git a/src/lib/json/json.c b/src/lib/json/json.c
index 46b67ba264adc..f8d2282130324 100644
--- a/src/lib/json/json.c
+++ b/src/lib/json/json.c
@@ -492,7 +492,7 @@ static int json_afrom_value_box(TALLOC_CTX *ctx, json_object **out,
 {
 	struct json_object	*obj;
 	fr_value_box_t const	*vb;
-	fr_value_box_t		vb_str;
+	fr_value_box_t		vb_str = FR_VALUE_BOX_INITIALISER_NULL(vb_str);
 	int			is_enum = 0;
 
 	fr_assert(vp);
diff --git a/src/lib/kafka/base.c b/src/lib/kafka/base.c
index 2fdc34b85180b..b3775d2ad57e3 100644
--- a/src/lib/kafka/base.c
+++ b/src/lib/kafka/base.c
@@ -323,7 +323,7 @@ static int kafka_topic_config_dflt(CONF_PAIR **out, void *parent, CONF_SECTION *
 
 static int kafka_config_parse_single(char const **out, CONF_PAIR *cp, CONF_PARSER const *rule)
 {
-	fr_value_box_t			vb;
+	fr_value_box_t			vb = FR_VALUE_BOX_INITIALISER_NULL(vb);
 	fr_kafka_conf_ctx_t const	*kctx = rule->uctx;
 	fr_type_t			type = FR_BASE_TYPE(rule->type);
 	static _Thread_local char	buff[sizeof("18446744073709551615")];
diff --git a/src/lib/server/tmpl_eval.c b/src/lib/server/tmpl_eval.c
index 55566578e3de4..d71a887d52659 100644
--- a/src/lib/server/tmpl_eval.c
+++ b/src/lib/server/tmpl_eval.c
@@ -280,8 +280,8 @@ ssize_t _tmpl_to_type(void *out,
 		      xlat_escape_legacy_t escape, void const *escape_ctx,
 		      fr_type_t dst_type)
 {
-	fr_value_box_t		value_to_cast;
-	fr_value_box_t		value_from_cast = { .type = FR_TYPE_NULL };
+	fr_value_box_t		value_to_cast = FR_VALUE_BOX_INITIALISER_NULL(value_to_cast);
+	fr_value_box_t		value_from_cast = FR_VALUE_BOX_INITIALISER_NULL(value_from_cast);
 	fr_value_box_t const	*to_cast = &value_to_cast;
 	fr_value_box_t const	*from_cast = &value_from_cast;
 
@@ -562,7 +562,7 @@ ssize_t _tmpl_to_atype(TALLOC_CTX *ctx, void *out,
 	fr_value_box_t		from_cast;
 
 	fr_pair_t		*vp = NULL;
-	fr_value_box_t		value = (fr_value_box_t){};
+	fr_value_box_t		value = FR_VALUE_BOX_INITIALISER_NULL(value);
 	bool			needs_dup = false;
 
 	ssize_t			slen = -1;
diff --git a/src/lib/util/dict_fixup.c b/src/lib/util/dict_fixup.c
index 0f15010ce0dea..5224d520c18fa 100644
--- a/src/lib/util/dict_fixup.c
+++ b/src/lib/util/dict_fixup.c
@@ -160,7 +160,7 @@ int dict_fixup_enumv(dict_fixup_ctx_t *fctx, char const *filename, int line,
 static inline CC_HINT(always_inline) int dict_fixup_enumv_apply(UNUSED dict_fixup_ctx_t *fctx, dict_fixup_enumv_t *fixup)
 {
 	fr_dict_attr_t 		*da;
-	fr_value_box_t		value;
+	fr_value_box_t		value = FR_VALUE_BOX_INITIALISER_NULL(value);
 	fr_type_t		type;
 	int			ret;
 	fr_dict_attr_t const	*da_const;
diff --git a/src/lib/util/dict_tokenize.c b/src/lib/util/dict_tokenize.c
index 1ab28c515bd6d..e1b15d9898182 100644
--- a/src/lib/util/dict_tokenize.c
+++ b/src/lib/util/dict_tokenize.c
@@ -1472,7 +1472,7 @@ static int dict_read_process_member(dict_tokenize_ctx_t *ctx, char **argv, int a
 static int dict_read_process_value(dict_tokenize_ctx_t *ctx, char **argv, int argc)
 {
 	fr_dict_attr_t		*da;
-	fr_value_box_t		value;
+	fr_value_box_t		value = FR_VALUE_BOX_INITIALISER_NULL(value);
 	fr_slen_t		enum_len;
 	fr_dict_attr_t const 	*parent = ctx->stack[ctx->stack_depth].da;
 
@@ -1598,7 +1598,7 @@ static int dict_read_process_struct(dict_tokenize_ctx_t *ctx, char **argv, int a
 	int				i;
 	fr_dict_attr_t const   		*da;
 	fr_dict_attr_t const	       	*parent = NULL;
-	fr_value_box_t			value;
+	fr_value_box_t			value = FR_VALUE_BOX_INITIALISER_NULL(value);
 	unsigned int			attr;
 	fr_dict_attr_flags_t		flags;
 	char				*key_attr = argv[1];
@@ -2799,7 +2799,7 @@ int fr_dict_internal_afrom_file(fr_dict_t **out, char const *dict_subdir, char c
 	fr_dict_attr_flags_t	flags = { .internal = true };
 	char			*type_name;
 	fr_dict_attr_t		*cast_base;
-	fr_value_box_t		box;
+	fr_value_box_t		box = FR_VALUE_BOX_INITIALISER_NULL(box);
 
 	if (unlikely(!dict_gctx)) {
 		fr_strerror_const("fr_dict_global_ctx_init() must be called before loading dictionary files");
diff --git a/src/lib/util/dlist.h b/src/lib/util/dlist.h
index 160024f207598..6400222f09ff3 100644
--- a/src/lib/util/dlist.h
+++ b/src/lib/util/dlist.h
@@ -64,6 +64,26 @@ typedef struct {
 
 static_assert(sizeof(unsigned int) >= 4, "Unsigned integer too small on this platform");
 
+/** Static initialiser for entries
+ *
+ @code {.c}
+   fr_dlist_entry_t my_entry = FR_DLIST_INITIALISER(my_entry)
+ @endcode
+ *
+ * @param[in] _entry	what's being initialised.
+ */
+#define FR_DLIST_ENTRY_INITIALISER(_entry) { .next = &_entry, .prev = &_entry }
+
+/** Static initialiser for list heads
+ *
+ @code {.c}
+   fr_dlist_head_t my_head = FR_DLIST_INITIALISER(my_head)
+ @endcode
+ *
+ * @param[in] _entry	what's being initialised.
+ */
+#define FR_DLIST_HEAD_INITIALISER(_head) { .entry = FR_DLIST_ENTRY_INITIALISER((_head).entry) }
+
 /** Iterate over the contents of a list
  *
  * @param[in] _list_head	to iterate over.
diff --git a/src/lib/util/value.c b/src/lib/util/value.c
index 78edae78712a0..27b322e1480c9 100644
--- a/src/lib/util/value.c
+++ b/src/lib/util/value.c
@@ -5941,6 +5941,10 @@ DIAG_ON(nonnull-compare)
 
 	if (vb->talloced) vb = talloc_get_type_abort_const(vb, fr_value_box_t);
 
+#ifndef NDEBUG
+	fr_fatal_assert_msg(vb->magic == FR_VALUE_BOX_MAGIC, "CONSISTENCY CHECK FAILED %s[%i]: fr_value_box_t magic "
+			    "incorrect, expected %" PRIx64 ", got %" PRIx64, file, line, FR_VALUE_BOX_MAGIC, vb->magic);
+#endif
 	switch (vb->type) {
 	case FR_TYPE_STRING:
 		fr_fatal_assert_msg(vb->vb_strvalue, "CONSISTENCY CHECK FAILED %s[%i]: fr_value_box_t strvalue field "
diff --git a/src/lib/util/value.h b/src/lib/util/value.h
index 1e31e3afda446..4ee74a2e37116 100644
--- a/src/lib/util/value.h
+++ b/src/lib/util/value.h
@@ -87,6 +87,10 @@ extern fr_sbuff_escape_rules_t *fr_value_escape_by_char[UINT8_MAX + 1];
 
 extern fr_sbuff_escape_rules_t fr_value_escape_unprintables;
 
+#ifndef NDEBUG
+#  define FR_VALUE_BOX_MAGIC RADIUSD_MAGIC_NUMBER
+#endif
+
 /** @name List and cursor type definitions
  */
 FR_DLIST_TYPES(fr_value_box_list)
@@ -170,8 +174,9 @@ struct value_box_s {
 	fr_value_box_datum_t			datum;			//!< The value held by the value box.  Should appear
 									///< last for packing efficiency.
 #ifndef NDEBUG
-	char const				*file;			//!< File where the box was allocated (if heap allocated).
-	int					line;			//!< Line where the box was allocated (if heap allocated).
+	uint64_t				magic;			//!< Value to verify that the structure was allocated or initialised properly.
+	char const				*file;			//!< File where the box was allocated or initialised.
+	int					line;			//!< Line where the box was allocated or initialised.
 #endif
 };
 
@@ -209,6 +214,12 @@ typedef enum {
 #define vb_should_free_value(_action)	((_action & FR_VALUE_BOX_LIST_FREE_BOX_VALUE) == FR_VALUE_BOX_LIST_FREE_BOX_VALUE)
 #define vb_should_remove(_action)	((_action & FR_VALUE_BOX_LIST_REMOVE) == FR_VALUE_BOX_LIST_REMOVE)
 
+#ifndef NDEBUG
+#define VALUE_BOX_NDEBUG_INITIALISER .file = __FILE__, .line = __LINE__, .magic = FR_VALUE_BOX_MAGIC
+#else
+#define VALUE_BOX_NDEBUG_INITIALISER
+#endif
+
 /** @name Field accessors for #fr_value_box_t
  *
  * Use these instead of accessing fields directly to make refactoring
@@ -258,7 +269,7 @@ typedef enum {
  *
  * @{
  */
-#define _fr_box_with_len(_type, _field, _val, _len) &(fr_value_box_t){ .type = _type, _field = _val, .vb_length = _len }
+#define _fr_box_with_len(_type, _field, _val, _len) &(fr_value_box_t){ .type = _type, _field = _val, .vb_length = _len, VALUE_BOX_NDEBUG_INITIALISER }
 
 #define fr_box_strvalue(_val)			_fr_box_with_len(FR_TYPE_STRING, .vb_strvalue, _val, strlen(_val))
 #define fr_box_strvalue_len(_val, _len)		_fr_box_with_len(FR_TYPE_STRING, .vb_strvalue, _val, _len)
@@ -267,7 +278,7 @@ typedef enum {
 #define fr_box_strvalue_buffer(_val)		_fr_box_with_len(FR_TYPE_STRING, .vb_strvalue, _val, talloc_array_length(_val) - 1)
 #define fr_box_octets_buffer(_val)		_fr_box_with_len(FR_TYPE_OCTETS, .vb_octets, _val, talloc_array_length(_val))
 
-#define _fr_box(_type, _field, _val) (&(fr_value_box_t){ .type = _type, _field = (_val) })
+#define _fr_box(_type, _field, _val) (&(fr_value_box_t){ .type = _type, _field = (_val), VALUE_BOX_NDEBUG_INITIALISER })
 
 #define fr_box_ipaddr(_val)			_fr_box((((_val).af == AF_INET) ? \
 							(((_val).prefix == 32) ?	FR_TYPE_IPV4_ADDR : \
@@ -453,6 +464,23 @@ extern fr_sbuff_parse_rules_t const *value_parse_rules_quoted_char[UINT8_MAX];
  *
  * @{
  */
+/** A static initialiser for stack/globally allocated boxes
+ *
+ * We can only safely initialise a null box, as many other type need special initialisation
+ */
+#define FR_VALUE_BOX_INITIALISER_NULL(_vb) \
+	{ \
+		.type = FR_TYPE_NULL, \
+		.datum = { \
+			.children = { \
+				FR_DLIST_HEAD_INITIALISER((_vb).datum.children.head) \
+			} \
+		}, \
+		.entry = { \
+			.entry = FR_DLIST_ENTRY_INITIALISER((_vb).entry.entry) \
+		}, \
+ 		VALUE_BOX_NDEBUG_INITIALISER \
+	}
 
 static inline CC_HINT(nonnull(1), always_inline)
 void _fr_value_box_init(NDEBUG_LOCATION_ARGS fr_value_box_t *vb, fr_type_t type, fr_dict_attr_t const *enumv, bool tainted)
@@ -501,6 +529,7 @@ void _fr_value_box_init(NDEBUG_LOCATION_ARGS fr_value_box_t *vb, fr_type_t type,
 	}
 
 #ifndef NDEBUG
+	vb->magic = FR_VALUE_BOX_MAGIC;
 	vb->file = file;
 	vb->line = line;
 #endif
diff --git a/src/protocols/dhcpv4/base.c b/src/protocols/dhcpv4/base.c
index 62b292324da54..90fa55ada5543 100644
--- a/src/protocols/dhcpv4/base.c
+++ b/src/protocols/dhcpv4/base.c
@@ -556,7 +556,7 @@ ssize_t fr_dhcpv4_encode_dbuff(fr_dbuff_t *dbuff, dhcp_packet_t *original, int c
  */
 int fr_dhcpv4_global_init(void)
 {
-	fr_value_box_t		value = { .type = FR_TYPE_UINT8 };
+	fr_value_box_t		value = *fr_box_uint8(0);
 	uint8_t			i;
 
 	if (instance_count > 0) {
diff --git a/src/protocols/dhcpv6/base.c b/src/protocols/dhcpv6/base.c
index 048cb025a8bdf..d7d122779cf80 100644
--- a/src/protocols/dhcpv6/base.c
+++ b/src/protocols/dhcpv6/base.c
@@ -907,7 +907,7 @@ void fr_dhcpv6_print_hex(FILE *fp, uint8_t const *packet, size_t packet_len)
 int fr_dhcpv6_global_init(void)
 {
 	fr_dict_attr_t const *child;
-	fr_value_box_t		value = { .type = FR_TYPE_UINT16 };
+	fr_value_box_t		value = *fr_box_uint16(0);
 
 	if (instance_count > 0) {
 		instance_count++;