diff --git a/support/support_capture_subprocess.c b/support/support_capture_subprocess.c
index 27bfd19c93..0bacf6dbc2 100644
--- a/support/support_capture_subprocess.c
+++ b/support/support_capture_subprocess.c
@@ -170,6 +170,7 @@ copy_and_spawn_sgid (char *child_id, gid_t gid)
      support_subprogram because we only want the program exit status, not the
      contents.  */
   ret = 0;
+  infd = outfd = -1;
 
   char * const args[] = {execname, child_id, NULL};