diff --git a/common/params_pyx.pyx b/common/params_pyx.pyx
index 64840640a4..7312a4d26e 100755
--- a/common/params_pyx.pyx
+++ b/common/params_pyx.pyx
@@ -1,10 +1,13 @@
 # distutils: langauge = c++
-import threading
-import os
+# cython: language_level = 3
 from libcpp cimport bool
 from libcpp.string cimport string
 from params_pxd cimport Params as c_Params
 
+import os
+import threading
+from common.basedir import PARAMS
+
 cdef enum TxType:
   PERSISTENT = 1
   CLEAR_ON_MANAGER_START = 2
@@ -81,11 +84,11 @@ class UnknownKeyName(Exception):
 cdef class Params:
   cdef c_Params* p
 
-  def __cinit__(self, d=None, persistent_params=False):
-    if d is not None:
-      self.p = new c_Params(<string>d.encode())
+  def __cinit__(self, d=PARAMS, bool persistent_params=False):
+    if persistent_params:
+      self.p = new c_Params(True)
     else:
-      self.p = new c_Params(<bool>persistent_params)
+      self.p = new c_Params(<string>d.encode())
 
   def __dealloc__(self):
     del self.p
diff --git a/selfdrive/common/params.cc b/selfdrive/common/params.cc
index 73839a6381..6c01598bd2 100644
--- a/selfdrive/common/params.cc
+++ b/selfdrive/common/params.cc
@@ -23,17 +23,17 @@
 
 namespace {
 
-template <typename T>
-T* null_coalesce(T* a, T* b) {
-  return a != NULL ? a : b;
+std::string getenv_default(const char* env_var, const char* default_val) {
+  const char* env_val = getenv(env_var);
+  return std::string(env_val != NULL ? env_val : default_val);
 }
 
-static const char* default_params_path = null_coalesce(const_cast<const char*>(getenv("PARAMS_PATH")), "/data/params");
+const std::string default_params_path = getenv_default("PARAMS_PATH", "/data/params");
 
 #ifdef QCOM
-static const char* persistent_params_path = null_coalesce(const_cast<const char*>(getenv("PERSISTENT_PARAMS_PATH")), "/persist/comma/params");
+const std::string persistent_params_path = getenv_default("PERSISTENT_PARAMS_PATH", "/persist/comma/params");
 #else
-static const char* persistent_params_path = default_params_path;
+const std::string persistent_params_path = default_params_path;
 #endif
 
 } //namespace
@@ -99,8 +99,7 @@ static int ensure_dir_exists(std::string path) {
 
 
 Params::Params(bool persistent_param){
-  const char * path = persistent_param ? persistent_params_path : default_params_path;
-  params_path = std::string(path);
+  params_path = persistent_param ? persistent_params_path : default_params_path;
 }
 
 Params::Params(std::string path) {