1 files changed, 5 insertions, 1 deletions
diff --git a/perl.h b/perl.h
index 9418b52cc0..de6185b401 100644
--- a/perl.h
+++ b/perl.h
@@ -496,12 +496,16 @@ register struct op *Perl_op asm(stringify(OP_IN_REGISTER));
 #   include <sys/param.h>
 #endif
 
-
 /* Use all the "standard" definitions? */
 #if defined(STANDARD_C) && defined(I_STDLIB)
 #   include <stdlib.h>
 #endif
 
+/* If this causes problems, set i_unistd=undef in the hint file.  */
+#ifdef I_UNISTD
+#   include <unistd.h>
+#endif
+
 #ifdef PERL_MICRO /* Last chance to export Perl_my_swap */
 #  define MYSWAP
 #endif