diff --git a/macros.pyproject b/macros.pyproject
index 6a54fb8..67afe89 100644
--- a/macros.pyproject
+++ b/macros.pyproject
@@ -15,17 +15,15 @@
 %pyproject_record %{_builddir}/pyproject-record
 
 %pyproject_wheel() %{expand:\\\
-export TMPDIR="${PWD}/%{_pyproject_builddir}"
-mkdir -p "${TMPDIR}"
-CFLAGS="${CFLAGS:-${RPM_OPT_FLAGS}}" LDFLAGS="${LDFLAGS:-${RPM_LD_FLAGS}}" \\\
+mkdir -p "${PWD}/%{_pyproject_builddir}"
+CFLAGS="${CFLAGS:-${RPM_OPT_FLAGS}}" LDFLAGS="${LDFLAGS:-${RPM_LD_FLAGS}}" TMPDIR="${PWD}/%{_pyproject_builddir}" \\\
 %{__python3} -m pip wheel --wheel-dir %{_pyproject_wheeldir} --no-deps --use-pep517 --no-build-isolation --disable-pip-version-check --no-clean --progress-bar off --verbose .
 }
 
 
 %pyproject_install() %{expand:\\\
 specifier=$(ls %{_pyproject_wheeldir}/*.whl | xargs basename --multiple | sed -E 's/([^-]+)-([^-]+)-.+\\\.whl/\\\1==\\\2/')
-export TMPDIR="${PWD}/%{_pyproject_builddir}"
-%{__python3} -m pip install --root %{buildroot} --no-deps --disable-pip-version-check --progress-bar off --verbose --ignore-installed --no-warn-script-location --no-index --no-cache-dir --find-links %{_pyproject_wheeldir} $specifier
+TMPDIR="${PWD}/%{_pyproject_builddir}" %{__python3} -m pip install --root %{buildroot} --no-deps --disable-pip-version-check --progress-bar off --verbose --ignore-installed --no-warn-script-location --no-index --no-cache-dir --find-links %{_pyproject_wheeldir} $specifier
 if [ -d %{buildroot}%{_bindir} ]; then
   %py3_shebang_fix %{buildroot}%{_bindir}/*
   rm -rfv %{buildroot}%{_bindir}/__pycache__
diff --git a/pyproject-rpm-macros.spec b/pyproject-rpm-macros.spec
index 8329f87..98578bc 100644
--- a/pyproject-rpm-macros.spec
+++ b/pyproject-rpm-macros.spec
@@ -12,7 +12,7 @@ License:        MIT
 # In other cases, such as backports, increment the point
 # release.
 Version:        0
-Release:        39.2%{?dist}
+Release:        40%{?dist}
 
 # Macro files
 Source001:      macros.pyproject
@@ -110,6 +110,9 @@ export HOSTNAME="rpmbuild"  # to speedup tox in network-less mock, see rhbz#1856
 %license LICENSE
 
 %changelog
+* Thu May 27 2021 Miro Hrončok <mhroncok@redhat.com> - 0-40
+- Don't leak $TMPDIR outside of pyproject macros
+
 * Thu Apr 22 2021 Miro Hrončok <mhroncok@redhat.com> - 0-39.2
 - Handle tox provision (tox.requires / tox.minversion)
 - Generate BuildRequires on extras in lower case
diff --git a/tests/python-clikit.spec b/tests/python-clikit.spec
index 4be859d..dbb0044 100644
--- a/tests/python-clikit.spec
+++ b/tests/python-clikit.spec
@@ -36,8 +36,15 @@ Summary:        %{summary}
 
 
 %install
+# Internal check that $TMPDIR is not changed
+TPMDIR_original="$TMPDIR"
+
 %pyproject_install
 
+# Internal check that $TMPDIR is not changed
+test "$TMPDIR" == "$TPMDIR_original"
+
+
 %check
 # Internal check that the RECORD and REQUESTED files are
 # always removed in %%pyproject_wheel