diff --git a/Include/cpython/initconfig.h b/Include/cpython/initconfig.h
index 666c1e4..09f9a29 100644
--- a/Include/cpython/initconfig.h
+++ b/Include/cpython/initconfig.h
@@ -153,6 +153,7 @@ typedef struct PyConfig {
     PyWideStringList warnoptions;
     int site_import;
     int bytes_warning;
+    int warn_default_encoding;
     int inspect;
     int interactive;
     int optimization_level;
diff --git a/Include/internal/pycore_initconfig.h b/Include/internal/pycore_initconfig.h
index 28cd570..4b009e8 100644
--- a/Include/internal/pycore_initconfig.h
+++ b/Include/internal/pycore_initconfig.h
@@ -102,6 +102,7 @@ typedef struct {
     int isolated;             /* -I option */
     int use_environment;      /* -E option */
     int dev_mode;             /* -X dev and PYTHONDEVMODE */
+    int warn_default_encoding;     /* -X warn_default_encoding and PYTHONWARNDEFAULTENCODING */
 } _PyPreCmdline;
 
 #define _PyPreCmdline_INIT \
diff --git a/Include/pyerrors.h b/Include/pyerrors.h
index 14129d3..f5d1c71 100644
--- a/Include/pyerrors.h
+++ b/Include/pyerrors.h
@@ -146,6 +146,7 @@ PyAPI_DATA(PyObject *) PyExc_FutureWarning;
 PyAPI_DATA(PyObject *) PyExc_ImportWarning;
 PyAPI_DATA(PyObject *) PyExc_UnicodeWarning;
 PyAPI_DATA(PyObject *) PyExc_BytesWarning;
+PyAPI_DATA(PyObject *) PyExc_EncodingWarning;
 PyAPI_DATA(PyObject *) PyExc_ResourceWarning;