-extern int fseeko (FILE *fp, off_t offset, int whence);
-# define fseek(fp, offset, whence) fseeko (fp, (off_t)(offset), whence)
+extern int fseeko (FILE *fp, off_t offset, int whence) _GL_ARG_NONNULL ((1));
+# if !@GNULIB_FSEEK@
+# undef fseek
+# define fseek(f,o,w) \
+ (GL_LINK_WARNING ("fseek cannot handle files larger than 4 GB " \
+ "on 32-bit platforms - " \
+ "use fseeko function for handling of large files"), \
+ fseeko (f, o, w))
+# endif