diff --git a/Python/pystate.c b/Python/pystate.c
index f2924a8..f0662fa 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -60,7 +60,12 @@
 
     _PyGC_Initialize(&runtime->gc);
     _PyEval_Initialize(&runtime->ceval);
-    PyPreConfig_InitPythonConfig(&runtime->preconfig);
+
+    runtime->preconfig.struct_size = sizeof(PyPreConfig);
+    PyStatus status = PyPreConfig_InitPythonConfig(&runtime->preconfig);
+    if (_PyStatus_EXCEPTION(status)) {
+        return status;
+    }
 
     runtime->gilstate.check_enabled = 1;
 
@@ -205,6 +210,7 @@
     interp->id_refcount = -1;
     interp->check_interval = 100;
 
+    interp->config.struct_size = sizeof(PyConfig);
     PyStatus status = PyConfig_InitPythonConfig(&interp->config);
     if (_PyStatus_EXCEPTION(status)) {
         /* Don't report status to caller: PyConfig_InitPythonConfig()