diff --git a/hack/btrfs_installed_tag.sh b/hack/btrfs_installed_tag.sh
index c4d99f37..f2f2b33c 100755
--- a/hack/btrfs_installed_tag.sh
+++ b/hack/btrfs_installed_tag.sh
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-cc -E - > /dev/null 2> /dev/null << EOF
+${CPP:-${CC:-cc} -E} ${CPPFLAGS} - > /dev/null 2> /dev/null << EOF
 #include <btrfs/ioctl.h>
 EOF
 if test $? -ne 0 ; then
diff --git a/hack/btrfs_tag.sh b/hack/btrfs_tag.sh
index 59cb969a..ea753d4d 100755
--- a/hack/btrfs_tag.sh
+++ b/hack/btrfs_tag.sh
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-cc -E - > /dev/null 2> /dev/null << EOF
+${CPP:-${CC:-cc} -E} ${CPPFLAGS} - > /dev/null 2> /dev/null << EOF
 #include <btrfs/version.h>
 EOF
 if test $? -ne 0 ; then
diff --git a/hack/libsubid_tag.sh b/hack/libsubid_tag.sh
index 0f98e061..b788796c 100755
--- a/hack/libsubid_tag.sh
+++ b/hack/libsubid_tag.sh
@@ -5,7 +5,8 @@ fi
 tmpdir="$PWD/tmp.$RANDOM"
 mkdir -p "$tmpdir"
 trap 'rm -fr "$tmpdir"' EXIT
-cc -o "$tmpdir"/libsubid_tag -x c - -l subid > /dev/null 2> /dev/null << EOF
+${CC:-cc} ${CPPFLAGS} ${CFLAGS} -o "$tmpdir"/libsubid_tag -x c - -l subid \
+	  > /dev/null 2> /dev/null << EOF
 #include <shadow/subid.h>
 #include <stdlib.h>
 int main() {