diff --git a/process.c b/process.c
index fb57df5623..62801e6835 100644
--- a/process.c
+++ b/process.c
@@ -916,6 +916,8 @@ do_waitpid(rb_pid_t pid, int *st, int flags)
 #endif
 }
 
+#define WAITPID_LOCK_ONLY ((struct waitpid_state *)-1)
+
 struct waitpid_state {
     struct list_node wnode;
     rb_execution_context_t *ec;
@@ -3923,12 +3925,13 @@ retry_fork_async_signal_safe(int *status, int *ep,
     volatile int try_gc = 1;
     struct child_handler_disabler_state old;
     int err;
+    rb_vm_t *vm = w && WAITPID_USE_SIGCHLD ? GET_VM() : 0;
 
     while (1) {
         prefork();
         disable_child_handler_before_fork(&old);
-        if (w && WAITPID_USE_SIGCHLD) {
-            rb_native_mutex_lock(&rb_ec_vm_ptr(w->ec)->waitpid_lock);
+        if (vm) {
+            rb_native_mutex_lock(&vm->waitpid_lock);
         }
 #ifdef HAVE_WORKING_VFORK
         if (!has_privilege())
@@ -3954,12 +3957,12 @@ retry_fork_async_signal_safe(int *status, int *ep,
 #endif
         }
 	err = errno;
-        if (w && WAITPID_USE_SIGCHLD) {
-            if (pid > 0) {
+        if (vm) {
+            if (pid > 0 && w != WAITPID_LOCK_ONLY) {
                 w->pid = pid;
-                list_add(&rb_ec_vm_ptr(w->ec)->waiting_pids, &w->wnode);
+                list_add(&vm->waiting_pids, &w->wnode);
             }
-            rb_native_mutex_unlock(&rb_ec_vm_ptr(w->ec)->waitpid_lock);
+            rb_native_mutex_unlock(&vm->waitpid_lock);
         }
 	disable_child_handler_fork_parent(&old);
         if (0 < pid) /* fork succeed, parent process */
@@ -3995,7 +3998,8 @@ fork_check_err(int *status, int (*chfunc)(void*, char *, size_t), void *charg,
     error_occurred = recv_child_error(ep[0], &err, errmsg, errmsg_buflen);
     if (error_occurred) {
         if (status) {
-            VM_ASSERT(w == 0 && "only used by extensions");
+            VM_ASSERT((w == 0 || w == WAITPID_LOCK_ONLY) &&
+                      "only used by extensions");
             rb_protect(proc_syswait, (VALUE)pid, status);
         }
         else if (!w) {
@@ -4340,7 +4344,7 @@ rb_spawn_process(struct rb_execarg *eargp, char *errmsg, size_t errmsg_buflen)
     rb_last_status_set((status & 0xff) << 8, 0);
     pid = 1;			/* dummy */
 # endif
-    if (eargp->waitpid_state) {
+    if (eargp->waitpid_state && eargp->waitpid_state != WAITPID_LOCK_ONLY) {
         eargp->waitpid_state->pid = pid;
     }
     rb_execarg_run_options(&sarg, NULL, errmsg, errmsg_buflen);
@@ -4369,6 +4373,15 @@ static rb_pid_t
 rb_execarg_spawn(VALUE execarg_obj, char *errmsg, size_t errmsg_buflen)
 {
     struct spawn_args args;
+    struct rb_execarg *eargp = rb_execarg_get(execarg_obj);
+
+    /*
+     * Prevent a race with MJIT where the compiler process where
+     * can hold an FD of ours in between vfork + execve
+     */
+    if (!eargp->waitpid_state && mjit_enabled) {
+        eargp->waitpid_state = WAITPID_LOCK_ONLY;
+    }
 
     args.execarg = execarg_obj;
     args.errmsg.ptr = errmsg;
diff --git a/test/ruby/test_process.rb b/test/ruby/test_process.rb
index 4c212c13f2..816751ec81 100644
--- a/test/ruby/test_process.rb
+++ b/test/ruby/test_process.rb
@@ -343,11 +343,6 @@ class TestProcess < Test::Unit::TestCase
   end
 
   def test_execopt_env_path
-    # http://ci.rvm.jp/results/trunk-mjit@silicon-docker/1455223
-    # http://ci.rvm.jp/results/trunk-mjit@silicon-docker/1450027
-    # http://ci.rvm.jp/results/trunk-mjit@silicon-docker/1469867
-    skip 'this randomly fails with MJIT' if RubyVM::MJIT.enabled?
-
     bug8004 = '[ruby-core:53103] [Bug #8004]'
     Dir.mktmpdir do |d|
       open("#{d}/tmp_script.cmd", "w") {|f| f.puts ": ;"; f.chmod(0755)}