diff --git a/src/core/error_handling.c b/src/core/error_handling.c
index f1e62614384..779707f8bac 100644
--- a/src/core/error_handling.c
+++ b/src/core/error_handling.c
@@ -5,6 +5,7 @@
 #include "error_handling.h"
 #include "jsproxy.h"
 #include "pyproxy.h"
+#include "python2js.h"
 #include <emscripten.h>
 #include <stdio.h>
 
@@ -57,10 +58,10 @@ set_error(PyObject* err)
 EM_JS_REF(
 JsRef,
 new_error,
-(const char* type, const char* msg, PyObject* err),
+(JsRef type, JsRef msg, PyObject* err),
 {
   return Hiwire.new_value(
-    new API.PythonError(UTF8ToString(type), UTF8ToString(msg), err));
+    new API.PythonError(Hiwire.get_value(type), Hiwire.get_value(msg), err));
 });
 // clang-format on
 
@@ -192,21 +193,23 @@ wrap_exception()
   PyObject* type = NULL;
   PyObject* value = NULL;
   PyObject* traceback = NULL;
-  PyObject* typestr = NULL;
+  PyObject* py_typestr = NULL;
+  JsRef js_typestr = NULL;
   PyObject* pystr = NULL;
+  JsRef jsstr = NULL;
   JsRef jserror = NULL;
   fetch_and_normalize_exception(&type, &value, &traceback);
   store_sys_last_exception(type, value, traceback);
 
-  typestr = _PyObject_GetAttrId(type, &PyId___qualname__);
-  FAIL_IF_NULL(typestr);
-  const char* typestr_utf8 = PyUnicode_AsUTF8(typestr);
-  FAIL_IF_NULL(typestr_utf8);
+  py_typestr = _PyObject_GetAttrId(type, &PyId___qualname__);
+  FAIL_IF_NULL(py_typestr);
+  js_typestr = python2js(py_typestr);
+  FAIL_IF_NULL(js_typestr);
   pystr = format_exception_traceback(type, value, traceback);
   FAIL_IF_NULL(pystr);
-  const char* pystr_utf8 = PyUnicode_AsUTF8(pystr);
-  FAIL_IF_NULL(pystr_utf8);
-  jserror = new_error(typestr_utf8, pystr_utf8, value);
+  jsstr = python2js(pystr);
+  FAIL_IF_NULL(jsstr);
+  jserror = new_error(js_typestr, jsstr, value);
   FAIL_IF_NULL(jserror);
 
   success = true;
@@ -220,13 +223,20 @@ wrap_exception()
       PySys_WriteStderr("\nOriginal exception was:\n");
       PyErr_Display(type, value, traceback);
     }
-    jserror = new_error(
-      "PyodideInternalError", "Error occurred while formatting traceback", 0);
+    Js_static_string(InternalError, "PyodideInternalError");
+    Js_static_string(error_formatting_tb,
+                     "Error occurred while formatting traceback");
+    jserror = new_error(JsString_FromId(&InternalError),
+                        JsString_FromId(&error_formatting_tb),
+                        0);
   }
   Py_CLEAR(type);
   Py_CLEAR(value);
   Py_CLEAR(traceback);
+  Py_CLEAR(py_typestr);
+  hiwire_CLEAR(js_typestr);
   Py_CLEAR(pystr);
+  hiwire_CLEAR(jsstr);
   return jserror;
 }
 
diff --git a/src/core/hiwire.c b/src/core/hiwire.c
index 12e27706c0d..222e53dbb64 100644
--- a/src/core/hiwire.c
+++ b/src/core/hiwire.c
@@ -868,33 +868,23 @@ EM_JS_REF(JsRef, JsObject_Get, (JsRef idobj, JsRef idkey), {
   return Hiwire.new_value(result);
 });
 
-EM_JS_REF(JsRef, JsObject_GetString, (JsRef idobj, const char* ptrkey), {
-  const jsobj = Hiwire.get_value(idobj);
-  const jskey = normalizeReservedWords(UTF8ToString(ptrkey));
-  const result = jsobj[jskey];
-  // clang-format off
-  if (result === undefined && !(jskey in jsobj)) {
-    // clang-format on
-    return ERROR_REF;
-  }
-  return Hiwire.new_value(result);
-});
-
 // clang-format off
 EM_JS_NUM(errcode,
-JsObject_SetString,
-(JsRef idobj, const char* ptrkey, JsRef idval),
+JsObject_Set,
+(JsRef idobj, JsRef idkey, JsRef idval),
 {
-  let jsobj = Hiwire.get_value(idobj);
-  let jskey = normalizeReservedWords(UTF8ToString(ptrkey));
-  let jsval = Hiwire.get_value(idval);
+  const jsobj = Hiwire.get_value(idobj);
+  const key = Hiwire.get_value(idkey);
+  const jskey = normalizeReservedWords(key);
+  const jsval = Hiwire.get_value(idval);
   jsobj[jskey] = jsval;
 });
 // clang-format on
 
-EM_JS_NUM(errcode, JsObject_DeleteString, (JsRef idobj, const char* ptrkey), {
-  let jsobj = Hiwire.get_value(idobj);
-  let jskey = normalizeReservedWords(UTF8ToString(ptrkey));
+EM_JS_NUM(errcode, JsObject_Delete, (JsRef idobj, JsRef idkey), {
+  const jsobj = Hiwire.get_value(idobj);
+  const key = Hiwire.get_value(idkey);
+  const jskey = normalizeReservedWords(key);
   delete jsobj[jskey];
 });
 
diff --git a/src/core/hiwire.h b/src/core/hiwire.h
index d68226fd52d..eeb0c4769c6 100644
--- a/src/core/hiwire.h
+++ b/src/core/hiwire.h
@@ -510,15 +510,6 @@ JsArray_Clear(JsRef idobj);
 JsRef
 JsObject_New();
 
-/**
- * Get an object member by string.
- *
- *
- * Returns: New reference
- */
-JsRef
-JsObject_GetString(JsRef idobj, const char* ptrname);
-
 JsRef
 JsObject_Get(JsRef idobj, JsRef name);
 
@@ -526,13 +517,13 @@ JsObject_Get(JsRef idobj, JsRef name);
  * Set an object member by string.
  */
 errcode WARN_UNUSED
-JsObject_SetString(JsRef idobj, const char* ptrname, JsRef idval);
+JsObject_Set(JsRef idobj, JsRef name, JsRef idval);
 
 /**
  * Delete an object member by string.
  */
 errcode WARN_UNUSED
-JsObject_DeleteString(JsRef idobj, const char* ptrname);
+JsObject_Delete(JsRef idobj, JsRef name);
 
 /**
  * Get the methods on an object, both on itself and what it inherits.
diff --git a/src/core/jsproxy.c b/src/core/jsproxy.c
index 2cdc9021a52..e8ca3327cca 100644
--- a/src/core/jsproxy.c
+++ b/src/core/jsproxy.c
@@ -345,6 +345,7 @@ JsProxy_GetAttr(PyObject* self, PyObject* attr)
     FAIL();
   }
   jskey = python2js(attr);
+  FAIL_IF_NULL(jskey);
 
   idresult = JsObject_Get(JsProxy_REF(self), jskey);
   if (idresult == NULL) {
@@ -378,10 +379,10 @@ JsProxy_SetAttr(PyObject* self, PyObject* attr, PyObject* pyvalue)
 {
   bool success = false;
   JsRef idvalue = NULL;
+  JsRef jskey = NULL;
 
   const char* key = PyUnicode_AsUTF8(attr);
   FAIL_IF_NULL(key);
-
   if (strncmp(key, "__", 2) == 0) {
     // Avoid creating reference loops between Python and JavaScript with js
     // modules. Such reference loops make it hard to avoid leaking memory.
@@ -392,16 +393,21 @@ JsProxy_SetAttr(PyObject* self, PyObject* attr, PyObject* pyvalue)
     }
   }
 
+  jskey = python2js(attr);
+  FAIL_IF_NULL(jskey);
+
   if (pyvalue == NULL) {
-    FAIL_IF_MINUS_ONE(JsObject_DeleteString(JsProxy_REF(self), key));
+    FAIL_IF_MINUS_ONE(JsObject_Delete(JsProxy_REF(self), jskey));
   } else {
     idvalue = python2js(pyvalue);
-    FAIL_IF_MINUS_ONE(JsObject_SetString(JsProxy_REF(self), key, idvalue));
+    FAIL_IF_NULL(idvalue);
+    FAIL_IF_MINUS_ONE(JsObject_Set(JsProxy_REF(self), jskey, idvalue));
   }
 
   success = true;
 finally:
   hiwire_CLEAR(idvalue);
+  hiwire_CLEAR(jskey);
   return success ? 0 : -1;
 }
 
@@ -2904,6 +2910,7 @@ JsMethod_ConvertArgs(PyObject* const* args,
   JsRef idargs = NULL;
   JsRef idarg = NULL;
   JsRef idkwargs = NULL;
+  JsRef namejs = NULL;
 
   idargs = JsArray_New();
   FAIL_IF_NULL(idargs);
@@ -2934,10 +2941,12 @@ JsMethod_ConvertArgs(PyObject* const* args,
   Py_ssize_t nkwargs = PyTuple_Size(kwnames);
   for (Py_ssize_t i = 0, k = nargs; i < nkwargs; ++i, ++k) {
     PyObject* name = PyTuple_GET_ITEM(kwnames, i); /* borrowed! */
-    const char* name_utf8 = PyUnicode_AsUTF8(name);
+    namejs = python2js(name);
+    FAIL_IF_NULL(namejs);
     idarg = python2js_track_proxies(args[k], proxies, false);
     FAIL_IF_NULL(idarg);
-    FAIL_IF_MINUS_ONE(JsObject_SetString(idkwargs, name_utf8, idarg));
+    FAIL_IF_MINUS_ONE(JsObject_Set(idkwargs, namejs, idarg));
+    hiwire_CLEAR(namejs);
     hiwire_CLEAR(idarg);
   }
   FAIL_IF_MINUS_ONE(JsArray_Push(idargs, idkwargs));
@@ -2947,6 +2956,7 @@ JsMethod_ConvertArgs(PyObject* const* args,
 finally:
   hiwire_CLEAR(idarg);
   hiwire_CLEAR(idkwargs);
+  hiwire_CLEAR(namejs);
   if (!success) {
     hiwire_CLEAR(idargs);
   }