diff --git a/CHANGES/9999.bugfix.rst b/CHANGES/9999.bugfix.rst
new file mode 100644
index 000000000..63cb8adcd
--- /dev/null
+++ b/CHANGES/9999.bugfix.rst
@@ -0,0 +1,2 @@
+Fixed crash in debug builds.
+
diff --git a/multidict/_multidict.c b/multidict/_multidict.c
index 73c002296..c418c9d50 100644
--- a/multidict/_multidict.c
+++ b/multidict/_multidict.c
@@ -397,7 +397,10 @@ multidict_repr(MultiDictObject *self)
     PyObject *name =
         PyObject_GetAttr((PyObject *)Py_TYPE(self), self->state->str_name);
     if (name == NULL) {
+        PyObject *etype, *evalue, *etraceback;
+        PyErr_Fetch(&etype, &evalue, &etraceback);
         Py_ReprLeave((PyObject *)self);
+        PyErr_Restore(etype, evalue, etraceback);
         return NULL;
     }
     PyObject *ret = md_repr(self, name, true, true);
@@ -539,6 +542,11 @@ static int
 multidict_tp_init(MultiDictObject *self, PyObject *args, PyObject *kwds)
 {
     mod_state *state = get_mod_state_by_def((PyObject *)self);
+    if (state == NULL) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "Failed to retrieve module state for MultiDict");
+        return -1;
+    }
     PyObject *arg = NULL;
     Py_ssize_t size =
         _multidict_extend_parse_args(state, args, kwds, "MultiDict", &arg);
@@ -997,6 +1005,12 @@ static int
 cimultidict_tp_init(MultiDictObject *self, PyObject *args, PyObject *kwds)
 {
     mod_state *state = get_mod_state_by_def((PyObject *)self);
+    if (state == NULL) {
+        PyErr_SetString(
+            PyExc_RuntimeError,
+            "Failed to retrieve module state for CIMultiDictProxy");
+        return -1;
+    }
     PyObject *arg = NULL;
     Py_ssize_t size =
         _multidict_extend_parse_args(state, args, kwds, "CIMultiDict", &arg);
@@ -1052,6 +1066,11 @@ multidict_proxy_tp_init(MultiDictProxyObject *self, PyObject *args,
                         PyObject *kwds)
 {
     mod_state *state = get_mod_state_by_def((PyObject *)self);
+    if (state == NULL) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "Failed to retrieve module state for MultiDict");
+        return -1;
+    }
     PyObject *arg = NULL;
     MultiDictObject *md = NULL;
 
@@ -1306,6 +1325,12 @@ cimultidict_proxy_tp_init(MultiDictProxyObject *self, PyObject *args,
                           PyObject *kwds)
 {
     mod_state *state = get_mod_state_by_def((PyObject *)self);
+    if (state == NULL) {
+        PyErr_SetString(
+            PyExc_RuntimeError,
+            "Failed to retrieve module state for CIMultiDictProxy");
+        return -1;
+    }
     PyObject *arg = NULL;
     MultiDictObject *md = NULL;
 
diff --git a/multidict/_multilib/state.h b/multidict/_multilib/state.h
index 4e2610b6c..76d610833 100644
--- a/multidict/_multilib/state.h
+++ b/multidict/_multilib/state.h
@@ -121,7 +121,12 @@ get_mod_state_by_def(PyObject *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
     PyObject *mod = PyType_GetModuleByDef(tp, &multidict_module);
-    assert(mod != NULL);
+    if (mod == NULL) {
+        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            PyErr_Clear();
+        }
+        return NULL;
+    }
     return get_mod_state(mod);
 }