diff --git a/src/core/ev.c b/src/core/ev.c
index 3476937e..05317e9b 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -2641,6 +2641,8 @@ int janet_make_pipe(JanetHandle handles[2], int mode) {
     return 0;
 #else
     if (pipe(handles)) return -1;
+    if (mode != 2 && fcntl(handles[0], F_SETFD, FD_CLOEXEC)) goto error;
+    if (mode != 1 && fcntl(handles[1], F_SETFD, FD_CLOEXEC)) goto error;
     if (mode != 2 && fcntl(handles[0], F_SETFL, O_NONBLOCK)) goto error;
     if (mode != 1 && fcntl(handles[1], F_SETFL, O_NONBLOCK)) goto error;
     return 0;
diff --git a/src/core/os.c b/src/core/os.c
index 02fcfda0..b675c635 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -970,18 +970,24 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, int is_spawn) {
     posix_spawn_file_actions_init(&actions);
     if (pipe_in != JANET_HANDLE_NONE) {
         posix_spawn_file_actions_adddup2(&actions, pipe_in, 0);
+        posix_spawn_file_actions_addclose(&actions, pipe_in);
     } else if (new_in != JANET_HANDLE_NONE) {
         posix_spawn_file_actions_adddup2(&actions, new_in, 0);
+        posix_spawn_file_actions_addclose(&actions, new_in);
     }
     if (pipe_out != JANET_HANDLE_NONE) {
         posix_spawn_file_actions_adddup2(&actions, pipe_out, 1);
+        posix_spawn_file_actions_addclose(&actions, pipe_out);
     } else if (new_out != JANET_HANDLE_NONE) {
         posix_spawn_file_actions_adddup2(&actions, new_out, 1);
+        posix_spawn_file_actions_addclose(&actions, new_out);
     }
     if (pipe_err != JANET_HANDLE_NONE) {
         posix_spawn_file_actions_adddup2(&actions, pipe_err, 2);
+        posix_spawn_file_actions_addclose(&actions, pipe_err);
     } else if (new_err != JANET_HANDLE_NONE) {
         posix_spawn_file_actions_adddup2(&actions, new_err, 2);
+        posix_spawn_file_actions_addclose(&actions, new_err);
     }
 
     pid_t pid;