diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
index 07d5daf4d9..05fa05aa3e 100644
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -1607,6 +1607,7 @@ PQsslAttribute(PGconn *conn, const char *attribute_name)
 #define BIO_set_data(bio, data) (bio->ptr = data)
 #endif
 
+/* protected by ssl_config_mutex */
 static BIO_METHOD *my_bio_methods;
 
 static int
@@ -1672,6 +1673,15 @@ my_sock_write(BIO *h, const char *buf, int size)
 static BIO_METHOD *
 my_BIO_s_socket(void)
 {
+	BIO_METHOD *res;
+
+#ifdef ENABLE_THREAD_SAFETY
+	if (pthread_mutex_lock(&ssl_config_mutex))
+		return NULL;
+#endif
+
+	res = my_bio_methods;
+
 	if (!my_bio_methods)
 	{
 		BIO_METHOD *biom = (BIO_METHOD *) BIO_s_socket();
@@ -1680,39 +1690,58 @@ my_BIO_s_socket(void)
 
 		my_bio_index = BIO_get_new_index();
 		if (my_bio_index == -1)
-			return NULL;
+			goto err;
 		my_bio_index |= (BIO_TYPE_DESCRIPTOR | BIO_TYPE_SOURCE_SINK);
-		my_bio_methods = BIO_meth_new(my_bio_index, "libpq socket");
-		if (!my_bio_methods)
-			return NULL;
+		res = BIO_meth_new(my_bio_index, "libpq socket");
+		if (!res)
+			goto err;
 
 		/*
 		 * As of this writing, these functions never fail. But check anyway,
 		 * like OpenSSL's own examples do.
 		 */
-		if (!BIO_meth_set_write(my_bio_methods, my_sock_write) ||
-			!BIO_meth_set_read(my_bio_methods, my_sock_read) ||
-			!BIO_meth_set_gets(my_bio_methods, BIO_meth_get_gets(biom)) ||
-			!BIO_meth_set_puts(my_bio_methods, BIO_meth_get_puts(biom)) ||
-			!BIO_meth_set_ctrl(my_bio_methods, BIO_meth_get_ctrl(biom)) ||
-			!BIO_meth_set_create(my_bio_methods, BIO_meth_get_create(biom)) ||
-			!BIO_meth_set_destroy(my_bio_methods, BIO_meth_get_destroy(biom)) ||
-			!BIO_meth_set_callback_ctrl(my_bio_methods, BIO_meth_get_callback_ctrl(biom)))
+		if (!BIO_meth_set_write(res, my_sock_write) ||
+			!BIO_meth_set_read(res, my_sock_read) ||
+			!BIO_meth_set_gets(res, BIO_meth_get_gets(biom)) ||
+			!BIO_meth_set_puts(res, BIO_meth_get_puts(biom)) ||
+			!BIO_meth_set_ctrl(res, BIO_meth_get_ctrl(biom)) ||
+			!BIO_meth_set_create(res, BIO_meth_get_create(biom)) ||
+			!BIO_meth_set_destroy(res, BIO_meth_get_destroy(biom)) ||
+			!BIO_meth_set_callback_ctrl(res, BIO_meth_get_callback_ctrl(biom)))
 		{
-			BIO_meth_free(my_bio_methods);
-			my_bio_methods = NULL;
-			return NULL;
+			goto err;
 		}
 #else
-		my_bio_methods = malloc(sizeof(BIO_METHOD));
-		if (!my_bio_methods)
-			return NULL;
-		memcpy(my_bio_methods, biom, sizeof(BIO_METHOD));
-		my_bio_methods->bread = my_sock_read;
-		my_bio_methods->bwrite = my_sock_write;
+		res = malloc(sizeof(BIO_METHOD));
+		if (!res)
+			goto err;
+		memcpy(res, biom, sizeof(BIO_METHOD));
+		res->bread = my_sock_read;
+		res->bwrite = my_sock_write;
 #endif
 	}
-	return my_bio_methods;
+
+	my_bio_methods = res;
+
+#ifdef ENABLE_THREAD_SAFETY
+	pthread_mutex_unlock(&ssl_config_mutex);
+#endif
+
+	return res;
+
+err:
+#ifdef HAVE_BIO_METH_NEW
+	if (res)
+		BIO_meth_free(res);
+#else
+	if (res)
+		free(res);
+#endif
+
+#ifdef ENABLE_THREAD_SAFETY
+	pthread_mutex_unlock(&ssl_config_mutex);
+#endif
+	return NULL;
 }
 
 /* This should exactly match OpenSSL's SSL_set_fd except for using my BIO */