diff --git a/sim_fio.c b/sim_fio.c
index d3ed57c2..4ab86d36 100644
--- a/sim_fio.c
+++ b/sim_fio.c
@@ -224,13 +224,14 @@ FILE *sim_fopen (const char *file, const char *mode)
 #if defined (VMS)
 return fopen (file, mode, "ALQ=32", "DEQ=4096",
         "MBF=6", "MBC=127", "FOP=cbt,tef", "ROP=rah,wbh", "CTX=stm");
-#elif defined (__linux) || defined (__linux__) || defined (__hpux)
+#elif (defined (__linux) || defined (__linux__) || defined (__hpux)) && !defined (DONT_DO_LARGEFILE)
 return fopen64 (file, mode);
 #else
 return fopen (file, mode);
 #endif
 }
 
+#if !defined (DONT_DO_LARGEFILE)
 /* 64b VMS */
 
 #if ((defined (__ALPHA) || defined (__ia64)) && defined (VMS) && (__DECC_VER >= 60590001)) || \
@@ -341,6 +342,7 @@ return (t_offset)(ftello (st));
 }
 
 #endif  /* end Apple OS/X */
+#endif /* !DONT_DO_LARGEFILE */
 
 /* Default: no OS-specific routine has been defined */
 
diff --git a/sim_fio.h b/sim_fio.h
index 8d0d988f..bacd1eb8 100644
--- a/sim_fio.h
+++ b/sim_fio.h
@@ -38,13 +38,17 @@
 #define fxwrite(a,b,c,d)        sim_fwrite (a, b, c, d)
 
 int32 sim_finit (void);
-#if defined (__linux) || defined (__linux__) || defined (__hpux) || \
-    (defined (VMS) && (defined (__ALPHA) || defined (__ia64)) && (__DECC_VER >= 60590001)) || \
-    ((defined(__sun) || defined(__sun__)) && defined(_LARGEFILE_SOURCE)) ||                \
-    defined (_WIN32) || defined (__APPLE__) || defined (__FreeBSD__) || defined(__NetBSD__) || defined (__OpenBSD__) 
+#if (defined (__linux) || defined (__linux__) || defined (__hpux) ||                           \
+     (defined (VMS) && (defined (__ALPHA) || defined (__ia64)) && (__DECC_VER >= 60590001)) || \
+     ((defined(__sun) || defined(__sun__)) && defined(_LARGEFILE_SOURCE)) ||                   \
+     defined (_WIN32) || defined (__APPLE__) ||                                                \
+     defined (__FreeBSD__) || defined(__NetBSD__) || defined (__OpenBSD__)) && !defined (DONT_DO_LARGEFILE)
 typedef t_int64        t_offset;
 #else
 typedef int32        t_offset;
+#if !defined (DONT_DO_LARGEFILE)
+#define DONT_DO_LARGEFILE 1
+#endif
 #endif
 FILE *sim_fopen (const char *file, const char *mode);
 int sim_fseek (FILE *st, t_addr offset, int whence);