diff -r ba14f8b61bd8 Modules/_ctypes/_ctypes.c
--- a/Modules/_ctypes/_ctypes.c	Wed Nov 16 16:13:13 2016 +0200
+++ b/Modules/_ctypes/_ctypes.c	Wed Nov 16 19:40:52 2016 +0200
@@ -728,8 +728,7 @@ PyCStructType_setattro(PyObject *self, P
         return -1;
 
     if (value && PyUnicode_Check(key) &&
-        /* XXX struni _PyUnicode_AsString can fail (also in other places)! */
-        0 == strcmp(_PyUnicode_AsString(key), "_fields_"))
+        _PyUnicode_EqualToASCIIString(key, "_fields_"))
         return PyCStructUnionType_update_stgdict(self, value, 1);
     return 0;
 }
@@ -743,7 +742,7 @@ UnionType_setattro(PyObject *self, PyObj
         return -1;
 
     if (PyUnicode_Check(key) &&
-        0 == strcmp(_PyUnicode_AsString(key), "_fields_"))
+        _PyUnicode_EqualToASCIIString(key, "_fields_"))
         return PyCStructUnionType_update_stgdict(self, value, 0);
     return 0;
 }
diff -r ba14f8b61bd8 Modules/_ctypes/callproc.c
--- a/Modules/_ctypes/callproc.c	Wed Nov 16 16:13:13 2016 +0200
+++ b/Modules/_ctypes/callproc.c	Wed Nov 16 19:40:52 2016 +0200
@@ -1666,7 +1666,9 @@ POINTER(PyObject *self, PyObject *cls)
         return result;
     }
     if (PyUnicode_CheckExact(cls)) {
-        char *name = _PyUnicode_AsString(cls);
+        const char *name = PyUnicode_AsUTF8(cls);
+        if (name == NULL)
+            return NULL;
         buf = PyMem_Malloc(strlen(name) + 3 + 1);
         if (buf == NULL)
             return PyErr_NoMemory();
diff -r ba14f8b61bd8 Modules/ossaudiodev.c
--- a/Modules/ossaudiodev.c	Wed Nov 16 16:13:13 2016 +0200
+++ b/Modules/ossaudiodev.c	Wed Nov 16 19:40:52 2016 +0200
@@ -929,11 +929,14 @@ static PyMethodDef oss_mixer_methods[] =
 static PyObject *
 oss_getattro(oss_audio_t *self, PyObject *nameobj)
 {
-    char *name = "";
+    const char *name = "";
     PyObject * rval = NULL;
 
-    if (PyUnicode_Check(nameobj))
-        name = _PyUnicode_AsString(nameobj);
+    if (PyUnicode_Check(nameobj)) {
+        name = PyUnicode_AsUTF8(nameobj);
+        if (name == NULL)
+            return NULL;
+    }
 
     if (strcmp(name, "closed") == 0) {
         rval = (self->fd == -1) ? Py_True : Py_False;
diff -r ba14f8b61bd8 Python/ast.c
--- a/Python/ast.c	Wed Nov 16 16:13:13 2016 +0200
+++ b/Python/ast.c	Wed Nov 16 19:40:52 2016 +0200
@@ -2118,17 +2118,19 @@ ast_for_atom(struct compiling *c, const 
                 errtype = "value error";
             if (errtype) {
                 char buf[128];
+                const char *s = NULL;
                 PyObject *type, *value, *tback, *errstr;
                 PyErr_Fetch(&type, &value, &tback);
                 errstr = PyObject_Str(value);
-                if (errstr) {
-                    char *s = _PyUnicode_AsString(errstr);
+                if (errstr)
+                    s = PyUnicode_AsUTF8(errstr);
+                if (s) {
                     PyOS_snprintf(buf, sizeof(buf), "(%s) %s", errtype, s);
-                    Py_DECREF(errstr);
                 } else {
                     PyErr_Clear();
                     PyOS_snprintf(buf, sizeof(buf), "(%s) unknown error", errtype);
                 }
+                Py_XDECREF(errstr);
                 ast_error(c, n, buf);
                 Py_DECREF(type);
                 Py_XDECREF(value);
diff -r ba14f8b61bd8 Python/importdl.c
--- a/Python/importdl.c	Wed Nov 16 16:13:13 2016 +0200
+++ b/Python/importdl.c	Wed Nov 16 19:40:52 2016 +0200
@@ -147,6 +147,10 @@ PyObject *
     /* Package context is needed for single-phase init */
     oldcontext = _Py_PackageContext;
     _Py_PackageContext = PyUnicode_AsUTF8(name_unicode);
+    if (_Py_PackageContext == NULL) {
+        _Py_PackageContext = oldcontext;
+        goto error;
+    }
     m = p0();
     _Py_PackageContext = oldcontext;