diff --git a/server.c b/server.c
index 467f7b1..e466ee2 100644
--- a/server.c
+++ b/server.c
@@ -327,8 +327,15 @@ int bus_broadcast_message(Bus *s, BusClient *sender_client, WireMsg *msg, WireCt
 
             uint32_t previous_cursor = ctx->byte_cursor;
             if (match_rule_check(sender_client, c->matches[j], msg, ctx) >= 0) {
-                TRYST(wire_compose_unicast_reply(reply_ctx, ctx, msg, sender_client->unique_name->name, false));
-                TRYST(send(c->fd, reply_ctx->data, reply_ctx->byte_cursor, 0));
+                struct iovec bufs[2] = {0};
+                uint8_t header_data[384];
+                WireCtx header_ctx = {
+                    .byte_cursor = 0,
+                    .data_len = 384,
+                    .data = header_data
+                };
+                TRYST(wire_compose_unicast_reply(ctx, msg, sender_client->unique_name->name, bufs, &header_ctx));
+                TRYST(writev(c->fd, bufs, sizeof(bufs) / sizeof(bufs[0])));
                 // TODO?
                 memset(reply_ctx->data, 0, reply_ctx->data_len);
             }
@@ -375,17 +382,17 @@ int bus_broadcast_signal(Bus *s, BusClient *client, WireCtx *ctx, WireMsg *msg)
 int bus_unicast_message(Bus *s, WireMsg *msg, WireCtx *ctx, char *target_name, char *sender_unique_name, WireCtx *reply_ctx)
 {
     BusClient *target = TRYPTR(bus_name_find_client(s, target_name));
-    TRYST(wire_compose_unicast_reply(reply_ctx, ctx, msg, sender_unique_name, true));
-
-    struct iovec bufs[] = {
-        { reply_ctx->data, reply_ctx->byte_cursor }, /* header made by wire_compose_unicast_reply */
-        { ctx->data + reply_ctx->byte_cursor, msg->body_length } /* body */
+    struct iovec bufs[2] = {0};
+    uint8_t header_data[384];
+    WireCtx header_ctx = {
+        .byte_cursor = 0,
+        .data_len = 384,
+        .data = header_data
     };
 
-    ctx->byte_cursor += msg->body_length;
-    reply_ctx->byte_cursor += msg->body_length;
-
+    TRYST(wire_compose_unicast_reply(ctx, msg, sender_unique_name, bufs, &header_ctx));
     TRYST(writev(target->fd, bufs, sizeof(bufs) / sizeof(bufs[0])));
+
     return 0;
 }
 
diff --git a/wire.c b/wire.c
index 9773015..63e2ed4 100644
--- a/wire.c
+++ b/wire.c
@@ -1,5 +1,6 @@
 #include <string.h>
 #include <stdio.h>
+#include <sys/uio.h>
 #include "try.h"
 #include "util.h"
 #include "wire.h"
@@ -131,7 +132,13 @@ int wire_parse_message(WireCtx *c, WireMsg *msg)
     msg->serial = *(uint32_t*)TRYPTR(wire_get_u32(c));
     msg->header_fields_length = *(uint32_t*)TRYPTR(wire_get_u32(c));
 
+    TRYPTR(wire_write_align(c, 8));
+
+    msg->header_length = c->byte_cursor;
     size_t header_fields_end = c->byte_cursor + msg->header_fields_length;
+    if (unlikely(header_fields_end >= c->data_len)) {
+        return -1;
+    }
 
     VERBOSE("start parse message: type=%d, no_reply_expected=%d\n", msg->type, msg->flags & DBUS_FLAG_NO_REPLY_EXPECTED);
 
@@ -412,134 +419,35 @@ int wire_compose_error(WireCtx *c, WireMsg *msg, const char *error_name)
     return 0;
 }
 
-int wire_compose_unicast_reply(WireCtx *c, WireCtx *msg_c, WireMsg *msg, char *sender_unique_name, bool partial)
+int wire_compose_unicast_reply(WireCtx *msg_c, WireMsg *msg, char *sender_unique_name, struct iovec bufs[2], WireCtx *header_ctx)
 {
-    TRYPTR(wire_set_u8(c, msg->endianness)); /* endianness */
-    TRYPTR(wire_set_u8(c, msg->type)); /* type */
-    TRYPTR(wire_set_u8(c, msg->flags)); /* flags */
-    TRYPTR(wire_set_u8(c, DBUS_PROTOCOL_VERSION)); /* protocol_version */
-    TRYPTR(wire_set_u32(c, msg->body_length)); /* body length */
-    TRYPTR(wire_set_u32(c, msg->serial)); /* serial */
-    uint32_t *header_fields_length = TRYPTR(wire_set_u32(c, 0)); /* header_fields_length */
+    TRYPTR(wire_set_u8(header_ctx, msg->endianness)); /* endianness */
+    TRYPTR(wire_set_u8(header_ctx, msg->type)); /* type */
+    TRYPTR(wire_set_u8(header_ctx, msg->flags)); /* flags */
+    TRYPTR(wire_set_u8(header_ctx, DBUS_PROTOCOL_VERSION)); /* protocol_version */
+    TRYPTR(wire_set_u32(header_ctx, msg->body_length)); /* body length */
+    TRYPTR(wire_set_u32(header_ctx, msg->serial)); /* serial */
+    uint32_t *header_fields_length = TRYPTR(wire_set_u32(header_ctx, 0)); /* header_fields_length */
 
-    uint32_t header_fields_start = c->byte_cursor;
+    TRYPTR(wire_write_align(header_ctx, 8));
 
-    switch (msg->type) {
-        case DBUS_MESSAGE_SIGNAL: /* through */
-        case DBUS_MESSAGE_METHOD_CALL: {
-            // these fields are required for DBUS_MESSAGE_METHOD_CALL, so we must (hackily) check for their presence
-            // interface is not strictly required by the spec, however we require it here anyways
-            WireMsgField *path_field = &msg->fields[DBUS_HEADER_FIELD_PATH];
-            WireMsgField *interface_field = &msg->fields[DBUS_HEADER_FIELD_INTERFACE];
-            WireMsgField *member_field = &msg->fields[DBUS_HEADER_FIELD_MEMBER];
-            WireMsgField *signature_field = &msg->fields[DBUS_HEADER_FIELD_SIGNATURE];
-            if (!path_field->present || !interface_field->present || !interface_field->present) {
-                return -1;
-            }
+    uint32_t header_fields_start = header_ctx->byte_cursor;
 
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_PATH));
-            TRYPTR(wire_set_signature_single_char(c, 'o'));
-            TRYPTR(wire_set_string(c, path_field->t.str));
-            TRYPTR(wire_write_align(c, 8));
+    TRYPTR(wire_set_u8(header_ctx, DBUS_HEADER_FIELD_SENDER));
+    TRYPTR(wire_set_signature_single_char(header_ctx, 's'));
+    TRYPTR(wire_set_string(header_ctx, sender_unique_name));
+    TRYPTR(wire_write_align(header_ctx, 8));
 
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_INTERFACE));
-            TRYPTR(wire_set_signature_single_char(c, 's'));
-            TRYPTR(wire_set_string(c, interface_field->t.str));
-            TRYPTR(wire_write_align(c, 8));
+    *header_fields_length = header_ctx->byte_cursor - header_fields_start + msg->header_fields_length;
 
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_MEMBER));
-            TRYPTR(wire_set_signature_single_char(c, 's'));
-            TRYPTR(wire_set_string(c, member_field->t.str));
-            TRYPTR(wire_write_align(c, 8));
-
-            if (signature_field->present) {
-                TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SIGNATURE));
-                TRYPTR(wire_set_signature_single_char(c, 'g'));
-                TRYPTR(wire_set_signature(c, signature_field->t.str));
-                TRYPTR(wire_write_align(c, 8));
-            }
-
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SENDER));
-            TRYPTR(wire_set_signature_single_char(c, 's'));
-            TRYPTR(wire_set_string(c, sender_unique_name));
-            // last element, don't align
-        } break;
-
-        case DBUS_MESSAGE_METHOD_RETURN: {
-            WireMsgField *reply_serial_field = &msg->fields[DBUS_HEADER_FIELD_REPLY_SERIAL];
-            if (!reply_serial_field->present) {
-                return -1;
-            }
-
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_REPLY_SERIAL));
-            TRYPTR(wire_set_signature_single_char(c, 'u'));
-            TRYPTR(wire_set_u32(c, reply_serial_field->t.u32));
-            TRYPTR(wire_write_align(c, 8));
-
-            WireMsgField *signature_field = &msg->fields[DBUS_HEADER_FIELD_SIGNATURE];
-            if (signature_field->present) {
-                TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SIGNATURE));
-                TRYPTR(wire_set_signature_single_char(c, 'g'));
-                TRYPTR(wire_set_signature(c, signature_field->t.str));
-                TRYPTR(wire_write_align(c, 8));
-            }
-
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SENDER));
-            TRYPTR(wire_set_signature_single_char(c, 's'));
-            TRYPTR(wire_set_string(c, sender_unique_name));
-            // last element, don't align
-        } break;
-
-        case DBUS_MESSAGE_ERROR: {
-            WireMsgField *reply_serial_field = &msg->fields[DBUS_HEADER_FIELD_REPLY_SERIAL];
-            WireMsgField *error_name_field = &msg->fields[DBUS_HEADER_FIELD_ERROR_NAME];
-            if (!reply_serial_field->present || !error_name_field->present) {
-                return -1;
-            }
-
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_REPLY_SERIAL));
-            TRYPTR(wire_set_signature_single_char(c, 'u'));
-            TRYPTR(wire_set_u32(c, reply_serial_field->t.u32));
-            TRYPTR(wire_write_align(c, 8));
-
-            WireMsgField *signature_field = &msg->fields[DBUS_HEADER_FIELD_SIGNATURE];
-            if (signature_field->present) {
-                TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SIGNATURE));
-                TRYPTR(wire_set_signature_single_char(c, 'g'));
-                TRYPTR(wire_set_signature(c, signature_field->t.str));
-                TRYPTR(wire_write_align(c, 8));
-            }
-
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_ERROR_NAME));
-            TRYPTR(wire_set_signature_single_char(c, 's'));
-            TRYPTR(wire_set_string(c, error_name_field->t.str));
-            TRYPTR(wire_write_align(c, 8));
-
-            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SENDER));
-            TRYPTR(wire_set_signature_single_char(c, 's'));
-            TRYPTR(wire_set_string(c, sender_unique_name));
-            // last element, don't align
-        } break;
-
-        default: {
-            return -1;
-        } break;
-    }
-
-    *header_fields_length = c->byte_cursor - header_fields_start;
-
-    // header ends on an 8 byte alignment
-    TRYPTR(wire_write_align(c, 8));
-
-    if (c->byte_cursor + msg->body_length >= c->data_len || msg_c->byte_cursor + msg->body_length >= msg_c->data_len) {
+    if (msg_c->byte_cursor + msg->body_length >= msg_c->data_len) {
         return -1;
     }
 
-    if (!partial) {
-        memcpy(&c->data[c->byte_cursor], &msg_c->data[msg_c->byte_cursor], msg->body_length);
-        c->byte_cursor += msg->body_length;
-        msg_c->byte_cursor += msg->body_length;
-    }
+    bufs[0] = (struct iovec){ header_ctx->data, header_ctx->byte_cursor };
+    bufs[1] = (struct iovec){ msg_c->data + msg->header_length, msg_c->byte_cursor + msg->body_length - msg->header_length };
+
+    msg_c->byte_cursor += msg->body_length;
 
     return 0;
 }
diff --git a/wire.h b/wire.h
index 4eb1ace..447d270 100644
--- a/wire.h
+++ b/wire.h
@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <stdint.h>
 #include <stdbool.h>
+#include <sys/uio.h>
 #include "util.h"
 #include "try.h"
 
@@ -57,7 +58,7 @@ typedef struct {
 #define WIRE_MESSAGE_MAX_HEADER_FIELDS 9
 typedef struct {
     uint8_t endianness, type, flags, protocol_version;
-    uint32_t body_length, serial, header_fields_length;
+    uint32_t body_length, serial, header_fields_length, header_length;
     uint8_t header_fields_count;
     WireMsgField fields[WIRE_MESSAGE_MAX_HEADER_FIELDS]; /* cannot have more than 9 header fields */
 } WireMsg;
@@ -128,7 +129,7 @@ char *wire_get_string_check(WireCtx *c, int min_length, int max_length);
 int wire_parse_message(WireCtx *c, WireMsg *msg);
 int wire_compose_reply(WireCtx *c, WireMsg *msg, const char *signature, uint32_t **out_body_length);
 int wire_compose_error(WireCtx *c, WireMsg *msg, const char *error_name);
-int wire_compose_unicast_reply(WireCtx *c, WireCtx *msg_c, WireMsg *msg, char *sender_unique_name, bool partial);
+int wire_compose_unicast_reply(WireCtx *msg_c, WireMsg *msg, char *sender_unique_name, struct iovec bufs[2], WireCtx *header_ctx);
 int wire_compose_signal(WireCtx *c, WireMsg *out_msg, const char *signature, const char *member, uint32_t **out_body_length);
 int wire_collect_strings(WireCtx *c, WireMsg *msg, WireMsgBodyString *strings, int strings_count);