diff --git a/Python/ceval.c b/Python/ceval.c
index ff67c83..3392cd0 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -240,13 +240,13 @@
 #endif
 #include "ceval_gil.h"
 
-static void
-ensure_tstate_not_null(const char *func, PyThreadState *tstate)
+void _Py_NO_RETURN
+_Py_FatalError_TstateNULL(const char *func)
 {
-    if (tstate == NULL) {
-        _Py_FatalErrorFunc(func,
-                           "current thread state is NULL (released GIL?)");
-    }
+    _Py_FatalErrorFunc(func,
+                       "the function must be called with the GIL held, "
+                       "but the GIL is released "
+                       "(the current Python thread state is NULL)");
 }
 
 
@@ -346,7 +346,7 @@
 {
     _PyRuntimeState *runtime = &_PyRuntime;
     PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
-    ensure_tstate_not_null(__func__, tstate);
+    _Py_EnsureTstateNotNULL(tstate);
 
     take_gil(tstate);
 }
@@ -375,7 +375,7 @@
 void
 PyEval_AcquireThread(PyThreadState *tstate)
 {
-    ensure_tstate_not_null(__func__, tstate);
+    _Py_EnsureTstateNotNULL(tstate);
 
     take_gil(tstate);
 
@@ -410,7 +410,7 @@
 _PyEval_ReInitThreads(_PyRuntimeState *runtime)
 {
     PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
-    ensure_tstate_not_null(__func__, tstate);
+    _Py_EnsureTstateNotNULL(tstate);
 
     struct _gil_runtime_state *gil = &runtime->ceval.gil;
     if (!gil_created(gil)) {
@@ -445,7 +445,7 @@
 {
     _PyRuntimeState *runtime = &_PyRuntime;
     PyThreadState *tstate = _PyThreadState_Swap(&runtime->gilstate, NULL);
-    ensure_tstate_not_null(__func__, tstate);
+    _Py_EnsureTstateNotNULL(tstate);
 
     struct _ceval_runtime_state *ceval = &runtime->ceval;
     struct _ceval_state *ceval2 = &tstate->interp->ceval;
@@ -457,7 +457,7 @@
 void
 PyEval_RestoreThread(PyThreadState *tstate)
 {
-    ensure_tstate_not_null(__func__, tstate);
+    _Py_EnsureTstateNotNULL(tstate);
 
     take_gil(tstate);
 
@@ -889,7 +889,7 @@
 PyObject* _Py_HOT_FUNCTION
 _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
 {
-    ensure_tstate_not_null(__func__, tstate);
+    _Py_EnsureTstateNotNULL(tstate);
 
 #ifdef DXPAIRS
     int lastopcode = 0;