diff --git a/src/if_py_both.h b/src/if_py_both.h
index 7b748b2..2903b0b 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -130,10 +130,11 @@
     {
 	PyObject	*bytes;
 
-	if (!(bytes = PyUnicode_AsEncodedString(obj, ENC_OPT, NULL)))
+	if (!(bytes = PyUnicode_AsEncodedString(obj, ENC_OPT,
+							   ERRORS_ENCODE_ARG)))
 	    return NULL;
 
-	if(PyBytes_AsStringAndSize(bytes, (char **) &str, NULL) == -1
+	if (PyBytes_AsStringAndSize(bytes, (char **) &str, NULL) == -1
 		|| str == NULL)
 	{
 	    Py_DECREF(bytes);
@@ -4243,7 +4244,8 @@
     }
     else if (PyUnicode_Check(obj))
     {
-	if (!(bytes = PyUnicode_AsEncodedString(obj, ENC_OPT, NULL)))
+	if (!(bytes = PyUnicode_AsEncodedString(obj, ENC_OPT,
+							   ERRORS_ENCODE_ARG)))
 	    return NULL;
 
 	if (PyBytes_AsStringAndSize(bytes, &str, &len) == -1
@@ -6290,11 +6292,11 @@
 	PyObject	*bytes;
 	char_u	*str;
 
-	bytes = PyUnicode_AsEncodedString(obj, ENC_OPT, NULL);
+	bytes = PyUnicode_AsEncodedString(obj, ENC_OPT, ERRORS_ENCODE_ARG);
 	if (bytes == NULL)
 	    return -1;
 
-	if(PyBytes_AsStringAndSize(bytes, (char **) &str, NULL) == -1)
+	if (PyBytes_AsStringAndSize(bytes, (char **) &str, NULL) == -1)
 	    return -1;
 	if (str == NULL)
 	    return -1;