diff --git a/lib/common.c b/lib/common.c
index 88bcabe5..86a38586 100644
--- a/lib/common.c
+++ b/lib/common.c
@@ -97,9 +97,9 @@ ec_master_t *ecrt_open_master(unsigned int master_index)
             master_index);
 
 #ifdef USE_RTDM
-    master->fd = rt_dev_open(path, O_RDWR);
+    master->fd = rt_dev_open(path, O_RDWR | O_CLOEXEC);
 #else
-    master->fd = open(path, O_RDWR);
+    master->fd = open(path, O_RDWR | O_CLOEXEC);
 #endif
     if (EC_IOCTL_IS_ERROR(master->fd)) {
         EC_PRINT_ERR("Failed to open %s: %s\n", path,