diff --git a/bootstrap.conf b/bootstrap.conf
index d029253d3a..0faa2e2217 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -40,6 +40,7 @@ environ
 fclose
 fcntl
 fcntl-h
+fdatasync
 ffs
 fnmatch
 fsync
diff --git a/configure.ac b/configure.ac
index df19445974..6a0936a9ba 100644
--- a/configure.ac
+++ b/configure.ac
@@ -135,12 +135,9 @@ AC_CHECK_SIZEOF([long])
 
 dnl Availability of various common functions (non-fatal if missing),
 dnl and various less common threadsafe functions
-AC_CHECK_FUNCS_ONCE([cfmakeraw fdatasync geteuid getgid getgrnam_r getmntent_r \
+AC_CHECK_FUNCS_ONCE([cfmakeraw geteuid getgid getgrnam_r getmntent_r \
   getpwuid_r getuid initgroups kill mmap posix_fallocate posix_memalign \
   regexec sched_getaffinity])
-if test $ac_cv_func_fdatasync = no; then
-  AC_DEFINE([fdatasync], [fsync], [Define to fsync if you lack fdatasync])
-fi
 
 dnl Availability of pthread functions (if missing, win32 threading is
 dnl assumed).  Because of $LIB_PTHREAD, we cannot use AC_CHECK_FUNCS_ONCE.