diff --git a/README.md b/README.md
index 04acf40..4b83779 100644
--- a/README.md
+++ b/README.md
@@ -133,9 +133,13 @@ in `%generate_buildrequires`. If not, you need to add:
 Limitations
 -----------
 
-
-This macro changes shebang lines of every Python script in `%{buildroot}%{_bindir}` to `#! %{__python3} %{py3_shbang_opt}` (`#! /usr/bin/python3 -s`).
-We plan to preserve existing Python flags in shebangs, but the work is not yet finished.
+`%pyproject_install` changes shebang lines of every Python script in `%{buildroot}%{_bindir}` to `#!%{__python3} %{py3_shbang_opt}` (`#!/usr/bin/python3 -s`).
+Existing Python flags in shebangs are preserved.
+For example `#!/usr/bin/python3 -Ru` will be updated to `#!/usr/bin/python3 -sRu`.
+Sometimes, this can interfere with tests that run such scripts directly by name,
+because in tests we usually rely on `PYTHONPATH` (and `-s` ignores that).
+Would this behavior be undesired for any reason,
+undefine `%{py3_shbang_opt}` to turn it of.
 
 Extras are currently ignored.
 
diff --git a/macros.pyproject b/macros.pyproject
index 056e76c..2d13729 100644
--- a/macros.pyproject
+++ b/macros.pyproject
@@ -9,7 +9,7 @@ CFLAGS="${CFLAGS:-${RPM_OPT_FLAGS}}" LDFLAGS="${LDFLAGS:-${RPM_LD_FLAGS}}" \\\
 %pyproject_install() %{expand:\\\
 %{__python3} -m pip install --root %{buildroot} --no-deps --disable-pip-version-check --progress-bar off --verbose --ignore-installed --no-warn-script-location %{_pyproject_wheeldir}/*.whl
 if [ -d %{buildroot}%{_bindir} ]; then
-  pathfix.py -pni "%{__python3} %{py3_shbang_opts}" %{buildroot}%{_bindir}/*
+  pathfix.py -pni "%{__python3}" -k%{?py3_shbang_opts: -a%{py3_shbang_opts_nodash}} %{buildroot}%{_bindir}/*
   rm -rfv %{buildroot}%{_bindir}/__pycache__
 fi
 if [ -d %{buildroot}%{python3_sitelib} ]; then
diff --git a/pyproject-rpm-macros.spec b/pyproject-rpm-macros.spec
index 6997652..c3f65fd 100644
--- a/pyproject-rpm-macros.spec
+++ b/pyproject-rpm-macros.spec
@@ -90,6 +90,7 @@ install -m 644 pyproject_buildrequires.py %{buildroot}%{_rpmconfigdir}/redhat/
 * Wed Feb 05 2020 Miro Hrončok <mhroncok@redhat.com> - 0-12
 - Fallback to setuptools.build_meta:__legacy__ backend instead of setuptools.build_meta
 - Properly handle backends with colon
+- Preserve existing flags in shebangs of Python files in /usr/bin
 
 * Thu Jan 30 2020 Fedora Release Engineering <releng@fedoraproject.org> - 0-11
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_32_Mass_Rebuild
diff --git a/tests/tldr.spec b/tests/tldr.spec
index 0b76ffa..aa66812 100644
--- a/tests/tldr.spec
+++ b/tests/tldr.spec
@@ -27,6 +27,7 @@ BuildRequires:  pyproject-rpm-macros
 
 %check
 test ! -d %{buildroot}%{_bindir}/__pycache__
+head -n1 %{buildroot}%{_bindir}/%{name}.py | egrep '#!\s*%{python3}\s+%{py3_shbang_opts}\s*$'
 
 %files
 %license LICENSE