diff --git a/tests/pressure-vessel/containers.py b/tests/pressure-vessel/containers.py
index b4e739dea85ca5ab29555950d7b4395b461720a2..2b9ca685b24b096db87e08d099fb291a39b27519 100755
--- a/tests/pressure-vessel/containers.py
+++ b/tests/pressure-vessel/containers.py
@@ -144,6 +144,7 @@ FILESYSTEM_ENV_VARS = [
     FilesystemEnvVar('STEAM_COMPAT_SHADER_PATH'),
     FilesystemEnvVar('STEAM_COMPAT_TOOL_PATH'),
     FilesystemEnvVar('STEAM_COMPAT_TOOL_PATHS', plural=True),
+    FilesystemEnvVar('STEAM_EXTRA_COMPAT_TOOLS_PATHS', plural=True),
 ]