diff --git a/src/os_unix.c b/src/os_unix.c
index d0a1c52..c062ad1 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -753,7 +753,8 @@
     if (signal_stack != NULL)
     {
 # ifdef HAVE_SIGALTSTACK
-#  ifdef __APPLE__
+#  if defined(__APPLE__) && (!defined(MAC_OS_X_VERSION_MAX_ALLOWED) \
+		|| MAC_OS_X_VERSION_MAX_ALLOWED <= 1040)
 	/* missing prototype.  Adding it to osdef?.h.in doesn't work, because
 	 * "struct sigaltstack" needs to be declared. */
 	extern int sigaltstack __ARGS((const struct sigaltstack *ss, struct sigaltstack *oss));
@@ -5688,7 +5689,7 @@
 
 /*
  * Closes connection to gpm
- * returns non-zero if connection succesfully closed
+ * returns non-zero if connection successfully closed
  */
     static void
 gpm_close()