diff --git a/configure.ac b/configure.ac
index 5f28e30..69d42ff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -186,9 +186,18 @@ dnl AC_PROG_CC
 dnl CFLAGS=$user_cflags
 MORECFLAGS=""
 dnl  we need  AC_SYS_LARGEFILE and AC_FUNC_FSEEKO
+LARGEFILECFLAGS=""
 AC_SYS_LARGEFILE
-AS_IF([test "x$ac_cv_sys_file_offset_bits" = xno],[ac_cv_sys_file_offset_bits=0])
-AC_SUBST(ac_cv_sys_file_offset_bits)
+dnl AS_IF([test "x$ac_cv_sys_file_offset_bits" = xno],[ac_cv_sys_file_offset_bits=0])
+dnl AC_SUBST(ac_cv_sys_file_offset_bits
+AS_CASE([$ac_cv_sys_largefile_opts],
+  ["none needed"], [],
+  ["support not detected"], [],
+  dnl otherwise it is a compiler flag
+  [LARGEFILECFLAGS="$ac_cv_sys_largefile_opts"]
+  )
+MORECFLAGS="$LARGEFILECFLAGS"
+AC_SUBST(LARGEFILECFLAGS)
 
 dnl AS_IF([test "x$user_cflags" = x || test "x$user_cflags" = x-m32],
 dnl [
diff --git a/nauty-h.in b/nauty-h.in
index ae65bc9..51508d9 100644
--- a/nauty-h.in
+++ b/nauty-h.in
@@ -60,13 +60,6 @@ it is necessary to check they are correct.
 #define FLEX_ARRAY_OK @flex_array_ok@
  /* whether the compiler supports flexible array members in structures */
 
-#define _FILE_OFFSET_BITS @ac_cv_sys_file_offset_bits@
-#if _FILE_OFFSET_BITS == 64
-#define _LARGEFILE_SOURCE
-#else
-#undef _FILE_OFFSET_BITS
-#endif
-
 /* Support of gcc extensions __builtin_clz, __builtin_clzl, __builtin_clzll */
 #ifndef HAVE_HWLZCNT
 #define HAVE_HWLZCNT @have_hwlzcnt@
diff --git a/nauty-pc.in b/nauty-pc.in
index cde86b3..c0bcef8 100644
--- a/nauty-pc.in
+++ b/nauty-pc.in
@@ -9,4 +9,4 @@ Version: @PACKAGE_VERSION@
 URL: @PACKAGE_URL@
 Libs: -L${libdir} -l@PACKAGE@
 Libs.private: -lpthread
-Cflags: -I${includedir}
+Cflags: -I${includedir} @LARGEFILECFLAGS@