diff --git a/packages/hxtorch/package.py b/packages/hxtorch/package.py
index 85022fb4d73a9796b8d6f76d839342e3c1ea2cc4..042f1e0422d585011569b9d46c72038d8c7a6d94 100644
--- a/packages/hxtorch/package.py
+++ b/packages/hxtorch/package.py
@@ -191,6 +191,6 @@ class Hxtorch(WafPackage):
         with working_dir('spack-test', create=True):
             old_pythonpath = os.environ.get('PYTHONPATH', '')
             os.environ['PYTHONPATH'] = ':'.join([str(self.prefix.lib), old_pythonpath])
-            bash = which(bash)
+            bash = which("bash")
             # ignore segfaults for now (exit code 139)
             bash('-c', '(python -c "import hxtorch; print(hxtorch.__file__)" || ( test $? -eq 139 && echo "segfault")) || exit $?')
diff --git a/packages/pynn-brainscales/package.py b/packages/pynn-brainscales/package.py
index 9e6607f3c17594d253ca9b86f0b2a9c6f1ee96d2..9b48b0dfe6a0ff4a4f18e1344cad353e17735948 100644
--- a/packages/pynn-brainscales/package.py
+++ b/packages/pynn-brainscales/package.py
@@ -168,6 +168,6 @@ class PynnBrainscales(WafPackage):
         with working_dir('spack-test', create=True):
             old_pythonpath = os.environ.get('PYTHONPATH', '')
             os.environ['PYTHONPATH'] = ':'.join([str(self.prefix.lib), old_pythonpath])
-            bash = which(bash)
+            bash = which("bash")
             # ignore segfaults for now (exit code 139)
             bash('-c', '(python -c "import pynn_brainscales; print(pynn_brainscales.__file__)" || ( test $? -eq 139 && echo "segfault")) || exit $?')