diff --git a/perl/Build.PL.in b/perl/Build.PL.in
index 0ab361738..13b3b453a 100755
--- a/perl/Build.PL.in
+++ b/perl/Build.PL.in
@@ -65,6 +65,8 @@ my $build = Module::Build->new (
         '@top_srcdir@/include',
     ],
     extra_linker_flags => [
+        '-DGUESTFS_PRIVATE=1',
+        split (' ', '@CFLAGS@'),
         '-L@top_builddir@/lib/.libs',
         '-lguestfs',
     ],