diff --git a/src/util.h b/src/util.h
index b95e75b..1774956 100644
--- a/src/util.h
+++ b/src/util.h
@@ -37,6 +37,7 @@
  * some Python.
  */
 #  define MY_BEGIN_ALLOW_THREADS(ignored)                               \
+    PyThread_delete_key_value(_pyOpenSSL_tstate_key);			\
     PyThread_set_key_value(_pyOpenSSL_tstate_key, PyEval_SaveThread());
 
 /*