diff --git a/osdep/subprocess-posix.c b/osdep/subprocess-posix.c
index 82af7c5f50..e56e2401f7 100644
--- a/osdep/subprocess-posix.c
+++ b/osdep/subprocess-posix.c
@@ -66,18 +66,18 @@ int mp_subprocess(char **args, struct mp_cancel *cancel, void *ctx,
     int p_stderr[2] = {-1, -1};
     pid_t pid = -1;
 
-    if (mp_make_cloexec_pipe(p_stdout) < 0)
+    if (on_stdout && mp_make_cloexec_pipe(p_stdout) < 0)
         goto done;
-    if (mp_make_cloexec_pipe(p_stderr) < 0)
+    if (on_stderr && mp_make_cloexec_pipe(p_stderr) < 0)
         goto done;
 
     if (posix_spawn_file_actions_init(&fa))
         goto done;
     fa_destroy = true;
     // redirect stdout and stderr
-    if (posix_spawn_file_actions_adddup2(&fa, p_stdout[1], 1))
+    if (p_stdout[1] >= 0 && posix_spawn_file_actions_adddup2(&fa, p_stdout[1], 1))
         goto done;
-    if (posix_spawn_file_actions_adddup2(&fa, p_stderr[1], 2))
+    if (p_stderr[1] >= 0 && posix_spawn_file_actions_adddup2(&fa, p_stderr[1], 2))
         goto done;
 
     if (posix_spawnp(&pid, args[0], &fa, NULL, args, environ)) {
diff --git a/osdep/subprocess-win.c b/osdep/subprocess-win.c
index bdc78c939d..9edfca0f45 100644
--- a/osdep/subprocess-win.c
+++ b/osdep/subprocess-win.c
@@ -220,6 +220,10 @@ static int async_read(HANDLE file, void *buf, unsigned size, OVERLAPPED* ol)
     return 0;
 }
 
+static void write_none(void *ctx, char *data, size_t size)
+{
+}
+
 int mp_subprocess(char **args, struct mp_cancel *cancel, void *ctx,
                   subprocess_read_cb on_stdout, subprocess_read_cb on_stderr,
                   char **error)
@@ -233,8 +237,8 @@ int mp_subprocess(char **args, struct mp_cancel *cancel, void *ctx,
         char buf[4096];
         subprocess_read_cb read_cb;
     } pipes[2] = {
-        { .read_cb = on_stdout },
-        { .read_cb = on_stderr },
+        { .read_cb = on_stdout ? on_stdout : write_none },
+        { .read_cb = on_stderr ? on_stderr : write_none },
     };
 
     // If the function exits before CreateProcess, there was an init error