diff --git a/master.inc b/master.inc
index cb20415..a599016 100644
--- a/master.inc
+++ b/master.inc
@@ -111,18 +111,18 @@ sed -i 's@KBUILD_IMAGE	:= $(boot)/Image.gz@KBUILD_IMAGE	:= $(boot)/Image@' arch/
 %{make} PYTHON=%{__python3} %{make_targets}
 
 %install
-rm -rf $RPM_BUILD_ROOT
-mkdir -p $RPM_BUILD_ROOT
+rm -rf %{buildroot}
+mkdir -p %{buildroot}
 
 # install the kernel
-mkdir -p $RPM_BUILD_ROOT/boot
-cp $(%{make} -s image_name) $RPM_BUILD_ROOT/boot/vmlinuz-%{KVERREL}
-chmod 755 $RPM_BUILD_ROOT/boot/vmlinuz-%{KVERREL}
-echo "%{KVERREL}" > $RPM_BUILD_ROOT/boot/.uname-%{KVERREL}
+mkdir -p %{buildroot}/boot
+cp $(%{make} -s image_name) %{buildroot}/boot/vmlinuz-%{KVERREL}
+chmod 755 %{buildroot}/boot/vmlinuz-%{KVERREL}
+echo "%{KVERREL}" > %{buildroot}/boot/.uname-%{KVERREL}
 
 # install DTBs
 %ifarch aarch64 || riscv64
-%{make} INSTALL_DTBS_PATH=$RPM_BUILD_ROOT/boot/dtb-%{KVERREL} dtbs_install
+%{make} INSTALL_DTBS_PATH=%{buildroot}/boot/dtb-%{KVERREL} dtbs_install
 # delete "arch/%{build_arch}/boot/dts" because "$PWD" will be packaged in "%devel"
 find arch/%{build_arch}/boot/dts -name '*.dtb' -type f -delete
 %endif
@@ -130,33 +130,33 @@ find arch/%{build_arch}/boot/dts -name '*.dtb' -type f -delete
 # install modules
 # '$(mod-fw)' is overridden because there is no reason to install any firmware
 # since we already have 'linux-firmware' package as the dependency of this package.
-%{make} INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=$RPM_BUILD_ROOT mod-fw= modules_install
+%{make} INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=%{buildroot} mod-fw= modules_install
 
 # install headers
-%{make} INSTALL_HDR_PATH=$RPM_BUILD_ROOT/usr headers_install
+%{make} INSTALL_HDR_PATH=%{buildroot}/usr headers_install
 
 # install other key files too
-install -m 644 .config $RPM_BUILD_ROOT/boot/config-%{KVERREL}
-install -m 644 .config $RPM_BUILD_ROOT/lib/modules/%{KVERREL}/config
-install -m 644 System.map $RPM_BUILD_ROOT/boot/System.map-%{KVERREL}
-install -m 644 System.map $RPM_BUILD_ROOT/lib/modules/%{KVERREL}/System.map
+install -m 644 .config %{buildroot}/boot/config-%{KVERREL}
+install -m 644 .config %{buildroot}/lib/modules/%{KVERREL}/config
+install -m 644 System.map %{buildroot}/boot/System.map-%{KVERREL}
+install -m 644 System.map %{buildroot}/lib/modules/%{KVERREL}/System.map
 
 # fix links
-rm -rf $RPM_BUILD_ROOT/lib/modules/%{KVERREL}/build
-rm -rf $RPM_BUILD_ROOT/lib/modules/%{KVERREL}/source
-ln -fns /usr/src/kernels/%{KVERREL} $RPM_BUILD_ROOT/lib/modules/%{KVERREL}/build
-ln -fns /usr/src/kernels/%{KVERREL} $RPM_BUILD_ROOT/lib/modules/%{KVERREL}/source
+rm -rf %{buildroot}/lib/modules/%{KVERREL}/build
+rm -rf %{buildroot}/lib/modules/%{KVERREL}/source
+ln -fns /usr/src/kernels/%{KVERREL} %{buildroot}/lib/modules/%{KVERREL}/build
+ln -fns /usr/src/kernels/%{KVERREL} %{buildroot}/lib/modules/%{KVERREL}/source
 
 # install actual Linux src to /usr/src/kernels/%{KVERREL}
-mkdir -p $RPM_BUILD_ROOT/usr/src/kernels/%{KVERREL}
+mkdir -p %{buildroot}/usr/src/kernels/%{KVERREL}
 if [ -f scripts/package/install-extmod-build ]; then
-    %{make} run-command KBUILD_RUN_COMMAND='${RPM_BUILD_DIR}/%{src_dir}/scripts/package/install-extmod-build $RPM_BUILD_ROOT/usr/src/kernels/%{KVERREL}'
+    %{make} run-command KBUILD_RUN_COMMAND='%{_builddir}/%{src_dir}/scripts/package/install-extmod-build %{buildroot}/usr/src/kernels/%{KVERREL}'
 else
-    touch $RPM_BUILD_ROOT/usr/src/kernels/%{KVERREL}/MAYBE_THIS_WORKS
+    touch %{buildroot}/usr/src/kernels/%{KVERREL}/MAYBE_THIS_WORKS
 fi
 
 %clean
-rm -rf $RPM_BUILD_ROOT
+rm -rf %{buildroot}
 
 %post
 set -xeuf -o pipefail