diff --git a/Lib/test/test_embed.py b/Lib/test/test_embed.py
index fe47289777a..da70df7914c 100644
--- a/Lib/test/test_embed.py
+++ b/Lib/test/test_embed.py
@@ -1349,7 +1349,7 @@ class AuditingTests(EmbeddingTestsMixin, unittest.TestCase):
                                       returncode=1)
 
     def test_audit_run_interactivehook(self):
-        startup = os.path.join(self.oldcwd, support.TESTFN) + ".py"
+        startup = os.path.join(self.oldcwd, support.TESTFN) + (support.TESTFN or '') + ".py"
         with open(startup, "w", encoding="utf-8") as f:
             print("import sys", file=f)
             print("sys.__interactivehook__ = lambda: None", file=f)
@@ -1362,7 +1362,7 @@ class AuditingTests(EmbeddingTestsMixin, unittest.TestCase):
             os.unlink(startup)
 
     def test_audit_run_startup(self):
-        startup = os.path.join(self.oldcwd, support.TESTFN) + ".py"
+        startup = os.path.join(self.oldcwd, support.TESTFN) + (support.TESTFN or '') + ".py"
         with open(startup, "w", encoding="utf-8") as f:
             print("pass", file=f)
         try:
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-06-23-23-26-42.bpo-41094.zEIJse.rst b/Misc/NEWS.d/next/Core and Builtins/2020-06-23-23-26-42.bpo-41094.zEIJse.rst
new file mode 100644
index 00000000000..6dd45e21d17
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-06-23-23-26-42.bpo-41094.zEIJse.rst	
@@ -0,0 +1,2 @@
+Fix decoding errors with audit when open files with non-ASCII names on non-UTF-8
+locale.
diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c
index af6e1e8ce0b..6030cc3d436 100644
--- a/Modules/_ctypes/callproc.c
+++ b/Modules/_ctypes/callproc.c
@@ -1415,15 +1415,12 @@ static PyObject *py_dl_open(PyObject *self, PyObject *args)
     if (name != Py_None) {
         if (PyUnicode_FSConverter(name, &name2) == 0)
             return NULL;
-        if (PyBytes_Check(name2))
-            name_str = PyBytes_AS_STRING(name2);
-        else
-            name_str = PyByteArray_AS_STRING(name2);
+        name_str = PyBytes_AS_STRING(name2);
     } else {
         name_str = NULL;
         name2 = NULL;
     }
-    if (PySys_Audit("ctypes.dlopen", "s", name_str) < 0) {
+    if (PySys_Audit("ctypes.dlopen", "O", name) < 0) {
         return NULL;
     }
     handle = ctypes_dlopen(name_str, mode);
diff --git a/Modules/main.c b/Modules/main.c
index bc3a2ed8ed8..8e3b35ca5ce 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -379,13 +379,20 @@ pymain_run_startup(PyConfig *config, PyCompilerFlags *cf, int *exitcode)
     if (startup == NULL) {
         return 0;
     }
-    if (PySys_Audit("cpython.run_startup", "s", startup) < 0) {
+    PyObject *startup_obj = PyUnicode_DecodeFSDefault(startup);
+    if (startup_obj == NULL) {
         return pymain_err_print(exitcode);
     }
+    if (PySys_Audit("cpython.run_startup", "O", startup_obj) < 0) {
+        Py_DECREF(startup_obj);
+        return pymain_err_print(exitcode);
+    }
+    Py_DECREF(startup_obj);
 
     FILE *fp = _Py_fopen(startup, "r");
     if (fp == NULL) {
         int save_errno = errno;
+        PyErr_Clear();
         PySys_WriteStderr("Could not open PYTHONSTARTUP\n");
 
         errno = save_errno;
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 22e72bdd5a9..2c86828ba98 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1274,7 +1274,12 @@ _Py_open_impl(const char *pathname, int flags, int gil_held)
 #endif
 
     if (gil_held) {
-        if (PySys_Audit("open", "sOi", pathname, Py_None, flags) < 0) {
+        PyObject *pathname_obj = PyUnicode_DecodeFSDefault(pathname);
+        if (pathname_obj == NULL) {
+            return -1;
+        }
+        if (PySys_Audit("open", "OOi", pathname_obj, Py_None, flags) < 0) {
+            Py_DECREF(pathname_obj);
             return -1;
         }
 
@@ -1284,12 +1289,16 @@ _Py_open_impl(const char *pathname, int flags, int gil_held)
             Py_END_ALLOW_THREADS
         } while (fd < 0
                  && errno == EINTR && !(async_err = PyErr_CheckSignals()));
-        if (async_err)
-            return -1;
-        if (fd < 0) {
-            PyErr_SetFromErrnoWithFilename(PyExc_OSError, pathname);
+        if (async_err) {
+            Py_DECREF(pathname_obj);
             return -1;
         }
+        if (fd < 0) {
+            PyErr_SetFromErrnoWithFilenameObjects(PyExc_OSError, pathname_obj, NULL);
+            Py_DECREF(pathname_obj);
+            return -1;
+        }
+        Py_DECREF(pathname_obj);
     }
     else {
         fd = open(pathname, flags);
@@ -1385,9 +1394,15 @@ _Py_wfopen(const wchar_t *path, const wchar_t *mode)
 FILE*
 _Py_fopen(const char *pathname, const char *mode)
 {
-    if (PySys_Audit("open", "ssi", pathname, mode, 0) < 0) {
+    PyObject *pathname_obj = PyUnicode_DecodeFSDefault(pathname);
+    if (pathname_obj == NULL) {
         return NULL;
     }
+    if (PySys_Audit("open", "Osi", pathname_obj, mode, 0) < 0) {
+        Py_DECREF(pathname_obj);
+        return NULL;
+    }
+    Py_DECREF(pathname_obj);
 
     FILE *f = fopen(pathname, mode);
     if (f == NULL)