Be consistent with how we do this elsewhereh
diff --git a/cryptography/hazmat/bindings/openssl/err.py b/cryptography/hazmat/bindings/openssl/err.py
index 56e9a6b..f2058ad 100644
--- a/cryptography/hazmat/bindings/openssl/err.py
+++ b/cryptography/hazmat/bindings/openssl/err.py
@@ -265,7 +265,7 @@
 #else
 static const long Cryptography_HAS_REMOVE_THREAD_STATE = 0;
 typedef uint32_t CRYPTO_THREADID;
-void (*ERR_remove_thread_state)(const CRYPTO_THREADID *);
+void (*ERR_remove_thread_state)(const CRYPTO_THREADID *) = NULL;
 #endif
 """