--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -157,9 +157,9 @@
 #endif
 #if defined(SIGTSTP)
 static RETSIGTYPE sig_tstp SIGPROTOARG;
+#endif
 // volatile because it is used in signal handler sig_tstp() and sigcont_handler().
 static volatile sig_atomic_t in_mch_suspend = FALSE;
-#endif
 #if defined(SIGINT)
 static RETSIGTYPE catch_sigint SIGPROTOARG;
 #endif