diff --git a/test/test.py b/test/test.py
index cc6a6a4..99b5f38 100644
--- a/test/test.py
+++ b/test/test.py
@@ -205,8 +205,8 @@ def test_python_interpreter():
 
 
 def test_python_interpreter_custom():
-    python_executable = sys.executable
-    configure_build_and_exe('python_interpreter_custom', 'python setup.py --cxx=g++ --python={}'.format(python_executable))
+    setup = 'python setup.py --cxx=g++ --python=%s' % sys.executable
+    configure_build_and_exe('python_interpreter_custom', setup)
 
 
 def test_python_libs():
@@ -214,5 +214,5 @@ def test_python_libs():
 
 
 def test_python_libs_custom():
-    python_executable = sys.executable
-    configure_build_and_exe('python_libs_custom', 'python setup.py --cxx=g++ --python={}'.format(python_executable))
+    setup = 'python setup.py --cxx=g++ --python=%s' % sys.executable
+    configure_build_and_exe('python_libs_custom', setup)