--- a/src/subprocess-posix.cc
+++ b/src/subprocess-posix.cc
@@ -72,6 +72,45 @@ bool Subprocess::Start(SubprocessSet* set, const string& command) {
     SetCloseOnExec(fd_);
   }
 
+#if defined(__redox__)
+  pid_ = fork();
+  if (pid_ < 0)
+    Fatal("fork: %s", strerror(errno));
+  if (pid_ == 0) {
+    if (sigprocmask(SIG_SETMASK, &set->old_mask_, 0) < 0) {
+      perror("ninja: sigprocmask");
+      _exit(1);
+    }
+    if (!use_console_) {
+      if (setpgid(0, 0) < 0) {
+        perror("ninja: setpgid");
+        _exit(1);
+      }
+      int devnull = open("/dev/null", O_RDONLY);
+      if (devnull < 0) {
+        perror("ninja: open /dev/null");
+        _exit(1);
+      }
+      if (dup2(devnull, 0) < 0 || dup2(subproc_stdout_fd, 1) < 0 ||
+          dup2(subproc_stdout_fd, 2) < 0) {
+        perror("ninja: dup2");
+        _exit(1);
+      }
+      close(devnull);
+      close(fd_);
+      close(subproc_stdout_fd);
+    }
+
+    const char* spawned_args[] = { "/bin/sh", "-c", command.c_str(), NULL };
+    execve("/bin/sh", const_cast<char**>(spawned_args), environ);
+    perror("ninja: execve /bin/sh");
+    _exit(127);
+  }
+
+  if (!use_console_)
+    close(subproc_stdout_fd);
+  return true;
+#else
   posix_spawn_file_actions_t action;
   int err = posix_spawn_file_actions_init(&action);
   if (err != 0)
@@ -145,6 +184,7 @@ bool Subprocess::Start(SubprocessSet* set, const string& command) {
   if (!use_console_)
     close(subproc_stdout_fd);
   return true;
+#endif
 }
 
 void Subprocess::OnPipeReady() {
--- a/src/util.cc
+++ b/src/util.cc
@@ -973,7 +973,7 @@ double GetLoadAverage() {
     return -0.0f;
   return 1.0 / (1 << SI_LOAD_SHIFT) * si.loads[0];
 }
-#elif defined(__HAIKU__)
+#elif defined(__HAIKU__) || defined(__redox__)
 double GetLoadAverage() {
     return -0.0f;
 }