diff --git a/tests/libqtest.c b/tests/libqtest.c
index 7012c5ccd0..af2a24e796 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -507,16 +507,6 @@ void qmp_fd_vsend(int fd, const char *fmt, va_list ap)
 {
     QObject *qobj;
 
-    /*
-     * qobject_from_vjsonf_nofail() chokes on leading 0xff as invalid
-     * JSON, but tests/test-qga.c needs to send that to test QGA
-     * synchronization
-     */
-    if (*fmt == '\377') {
-        socket_send(fd, fmt, 1);
-        fmt++;
-    }
-
     /* Going through qobject ensures we escape strings properly */
     qobj = qobject_from_vjsonf_nofail(fmt, ap);
 
@@ -604,23 +594,36 @@ void qtest_qmp_send(QTestState *s, const char *fmt, ...)
     va_end(ap);
 }
 
-void qtest_qmp_send_raw(QTestState *s, const char *fmt, ...)
+void qmp_fd_vsend_raw(int fd, const char *fmt, va_list ap)
 {
     bool log = getenv("QTEST_LOG") != NULL;
-    va_list ap;
-    char *str;
-
-    va_start(ap, fmt);
-    str = g_strdup_vprintf(fmt, ap);
-    va_end(ap);
+    char *str = g_strdup_vprintf(fmt, ap);
 
     if (log) {
         fprintf(stderr, "%s", str);
     }
-    socket_send(s->qmp_fd, str, strlen(str));
+    socket_send(fd, str, strlen(str));
     g_free(str);
 }
 
+void qmp_fd_send_raw(int fd, const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, fmt);
+    qmp_fd_vsend_raw(fd, fmt, ap);
+    va_end(ap);
+}
+
+void qtest_qmp_send_raw(QTestState *s, const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, fmt);
+    qmp_fd_vsend_raw(s->qmp_fd, fmt, ap);
+    va_end(ap);
+}
+
 QDict *qtest_qmp_eventwait_ref(QTestState *s, const char *event)
 {
     QDict *response;
diff --git a/tests/libqtest.h b/tests/libqtest.h
index 0a401a5380..36d5caecd4 100644
--- a/tests/libqtest.h
+++ b/tests/libqtest.h
@@ -959,6 +959,8 @@ static inline int64_t clock_set(int64_t val)
 QDict *qmp_fd_receive(int fd);
 void qmp_fd_vsend(int fd, const char *fmt, va_list ap) GCC_FMT_ATTR(2, 0);
 void qmp_fd_send(int fd, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
+void qmp_fd_send_raw(int fd, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
+void qmp_fd_vsend_raw(int fd, const char *fmt, va_list ap) GCC_FMT_ATTR(2, 0);
 QDict *qmp_fdv(int fd, const char *fmt, va_list ap) GCC_FMT_ATTR(2, 0);
 QDict *qmp_fd(int fd, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
 
diff --git a/tests/test-qga.c b/tests/test-qga.c
index c552cc0125..f69cdf6c03 100644
--- a/tests/test-qga.c
+++ b/tests/test-qga.c
@@ -147,8 +147,9 @@ static void test_qga_sync_delimited(gconstpointer fix)
     unsigned char c;
     QDict *ret;
 
+    qmp_fd_send_raw(fixture->fd, "\xff");
     qmp_fd_send(fixture->fd,
-                "\xff{'execute': 'guest-sync-delimited',"
+                "{'execute': 'guest-sync-delimited',"
                 " 'arguments': {'id': %u } }",
                 r);