diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 32d67b0..0deffa0 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -2245,6 +2245,10 @@
        argtypes would be a ctypes type).
     */
     stgdict->format = _ctypes_alloc_format_string(NULL, "X{}");
+    if (stgdict->format == NULL) {
+        Py_DECREF((PyObject *)stgdict);
+        return NULL;
+    }
     stgdict->flags |= TYPEFLAG_ISPOINTER;
 
     /* create the new instance (which is a class,