diff -ru mosquitto_pyauth-orig/auth_plugin_pyauth.c mosquitto_pyauth/auth_plugin_pyauth.c
--- mosquitto_pyauth-orig/auth_plugin_pyauth.c	2022-03-07 22:54:24.061601718 +0000
+++ mosquitto_pyauth/auth_plugin_pyauth.c	2022-03-07 23:08:29.649730300 +0000
@@ -300,7 +300,7 @@
     return MOSQ_ERR_SUCCESS;
 }
 
-int mosquitto_auth_acl_check(void *user_data, int access, const struct mosquitto *client, const struct mosquitto_acl_msg *msg)
+int mosquitto_auth_acl_check(void *user_data, int access, struct mosquitto *client, const struct mosquitto_acl_msg *msg)
 {
     struct pyauth_data *data = user_data;
 
@@ -327,7 +327,7 @@
     return ok ? MOSQ_ERR_SUCCESS : MOSQ_ERR_ACL_DENIED;
 }
 
-int mosquitto_auth_unpwd_check(void *user_data, const struct mosquitto *client unused, const char *username, const char *password)
+int mosquitto_auth_unpwd_check(void *user_data, struct mosquitto *client unused, const char *username, const char *password)
 {
     struct pyauth_data *data = user_data;
 
@@ -352,7 +352,7 @@
 }
 
 int mosquitto_auth_psk_key_get(void *user_data,
-                               const struct mosquitto *client unused,
+                               struct mosquitto *client unused,
                                const char *hint,
                                const char *identity,
                                char *key,
diff -ru mosquitto_pyauth-orig/Makefile mosquitto_pyauth/Makefile
--- mosquitto_pyauth-orig/Makefile	2022-03-07 22:54:24.057601774 +0000
+++ mosquitto_pyauth/Makefile	2022-03-07 23:11:06.671525832 +0000
@@ -1,5 +1,5 @@
 MOSQUITTO_SRC ?= ./
-PYTHON_VERSION ?= 3.6
+PYTHON_VERSION ?= 3
 
 PYTHON_CONFIG = python$(PYTHON_VERSION)-config
 
@@ -17,8 +17,8 @@
 CFLAGS += -I$(MOSQUITTO_SRC)/src/
 CFLAGS += -I$(MOSQUITTO_SRC)/lib/
 
-#LDFLAGS =-lmosquitto
-LDFLAGS += -L$(MOSQUITTO_SRC)/lib/
+LDFLAGS =-lmosquitto `$(PYTHON_CONFIG) --embed --ldflags`
+#LDFLAGS += -L$(MOSQUITTO_SRC)/lib/
 
 all : auth_plugin_pyauth.so