diff --git a/c_src/wterl.c b/c_src/wterl.c
index e2f4ffa..9131a8f 100644
--- a/c_src/wterl.c
+++ b/c_src/wterl.c
@@ -25,6 +25,7 @@
 #include <stdarg.h>
 #include <inttypes.h>
 #include <errno.h>
+#include <pthread.h>
 
 #include "wiredtiger.h"
 
@@ -57,7 +58,7 @@ typedef struct wterl_conn {
     WT_CONNECTION *conn;
     const char *session_config;
     STAILQ_HEAD(ctxs, wterl_ctx) cache;
-    ErlNifMutex *cache_mutex;
+    pthread_mutex_t cache_mutex;
     uint32_t cache_size;
 } WterlConnHandle;
 
@@ -69,11 +70,11 @@ typedef struct {
 struct wterl_event_handlers {
     WT_EVENT_HANDLER handlers;
     ErlNifEnv *msg_env_error;
-    ErlNifMutex *error_mutex;
+    pthread_mutex_t error_mutex;
     ErlNifEnv *msg_env_message;
-    ErlNifMutex *message_mutex;
+    pthread_mutex_t message_mutex;
     ErlNifEnv *msg_env_progress;
-    ErlNifMutex *progress_mutex;
+    pthread_mutex_t progress_mutex;
     ErlNifPid to_pid;
 };
 
@@ -204,7 +205,7 @@ __ctx_cache_evict(WterlConnHandle *conn_handle)
             STAILQ_REMOVE(&conn_handle->cache, c, wterl_ctx, entries);
             if (c->session)
                 c->session->close(c->session, NULL);
-            enif_free(c);
+            free(c);
             num_evicted++;
         }
     }
@@ -226,7 +227,7 @@ __ctx_cache_find(WterlConnHandle *conn_handle, const uint64_t sig)
 {
     struct wterl_ctx *c;
 
-    enif_mutex_lock(conn_handle->cache_mutex);
+    pthread_mutex_lock(&conn_handle->cache_mutex);
     c = STAILQ_FIRST(&conn_handle->cache);
     while (c != NULL) {
         if (c->sig == sig) { // TODO: hash collisions *will* lead to SEGVs
@@ -237,7 +238,7 @@ __ctx_cache_find(WterlConnHandle *conn_handle, const uint64_t sig)
         }
         c = STAILQ_NEXT(c, entries);
     }
-    enif_mutex_unlock(conn_handle->cache_mutex);
+    pthread_mutex_unlock(&conn_handle->cache_mutex);
     DPRINTF("cache_find: [%u] %s (%p)", conn_handle->cache_size, c ? "hit" : "miss", c);
     return c;
 }
@@ -251,7 +252,7 @@ __ctx_cache_find(WterlConnHandle *conn_handle, const uint64_t sig)
 static void
 __ctx_cache_add(WterlConnHandle *conn_handle, struct wterl_ctx *c)
 {
-    enif_mutex_lock(conn_handle->cache_mutex);
+    pthread_mutex_lock(&conn_handle->cache_mutex);
     __ctx_cache_evict(conn_handle);
     STAILQ_INSERT_TAIL(&conn_handle->cache, c, entries);
     conn_handle->cache_size += 1;
@@ -262,7 +263,7 @@ __ctx_cache_add(WterlConnHandle *conn_handle, struct wterl_ctx *c)
         sz++;
     }
 #endif
-    enif_mutex_unlock(conn_handle->cache_mutex);
+    pthread_mutex_unlock(&conn_handle->cache_mutex);
     DPRINTF("cache_add: [%u:%u] (%p)", sz, conn_handle->cache_size, c);
 }
 
@@ -333,7 +334,7 @@ __retain_ctx(WterlConnHandle *conn_handle, uint32_t worker_id,
 	int rc = conn->open_session(conn, NULL, session_config, &session);
 	if (rc != 0) return rc;
 	size_t s = sizeof(struct wterl_ctx) + (count * sizeof(struct cursor_info)) + sig_len;
-	c = enif_alloc(s); // TODO: enif_alloc_resource()
+	c = malloc(s); // TODO: enif_alloc_resource()
 	if (c == NULL) {
 	    session->close(session, NULL);
 	    return ENOMEM;
@@ -355,7 +356,7 @@ __retain_ctx(WterlConnHandle *conn_handle, uint32_t worker_id,
 	    c->ci[i].config = __copy_str_into(&p, config);
 	    rc = session->open_cursor(session, uri, NULL, config, &c->ci[i].cursor);
 	    if (rc != 0) {
-		enif_free(c);
+		free(c);
 		session->close(session, NULL); // this will free the cursors too
 		va_end(ap);
 		return rc;
@@ -391,7 +392,7 @@ __release_ctx(WterlConnHandle *conn_handle, uint32_t worker_id, struct wterl_ctx
 /**
  * Close all sessions and all cursors open on any objects.
  *
- * Note: always call within enif_mutex_lock/unlock(conn_handle->cache_mutex)
+ * Note: always call within pthread_mutex_lock/unlock(conn_handle->cache_mutex)
  */
 void
 __close_all_sessions(WterlConnHandle *conn_handle)
@@ -405,7 +406,7 @@ __close_all_sessions(WterlConnHandle *conn_handle)
         STAILQ_REMOVE(&conn_handle->cache, c, wterl_ctx, entries);
         conn_handle->cache_size -= 1;
         c->session->close(c->session, NULL);
-        enif_free(c);
+        free(c);
         c = n;
     }
 }
@@ -413,7 +414,7 @@ __close_all_sessions(WterlConnHandle *conn_handle)
 /**
  * Close cursors open on 'uri' object.
  *
- * Note: always call within enif_mutex_lock/unlock(conn_handle->cache_mutex)
+ * Note: always call within pthread_mutex_lock/unlock(conn_handle->cache_mutex)
  */
 void
 __close_cursors_on(WterlConnHandle *conn_handle, const char *uri)
@@ -431,7 +432,7 @@ __close_cursors_on(WterlConnHandle *conn_handle, const char *uri)
                 STAILQ_REMOVE(&conn_handle->cache, c, wterl_ctx, entries);
                 conn_handle->cache_size -= 1;
                 c->session->close(c->session, NULL);
-                enif_free(c);
+                free(c);
                 break;
             }
         }
@@ -461,7 +462,7 @@ __wterl_error_handler(WT_EVENT_HANDLER *handler, int error, const char *message)
     ErlNifPid *to_pid;
     int rc = 0;
 
-    enif_mutex_lock(eh->error_mutex);
+    pthread_mutex_lock(&eh->error_mutex);
     msg_env = eh->msg_env_error;
     to_pid = &eh->to_pid;
     if (msg_env) {
@@ -476,7 +477,7 @@ __wterl_error_handler(WT_EVENT_HANDLER *handler, int error, const char *message)
     } else {
         rc = (fprintf(stderr, "[%d] %s\n", error, message) >= 0 ? 0 : EIO);
     }
-    enif_mutex_unlock(eh->error_mutex);
+    pthread_mutex_unlock(&eh->error_mutex);
     return rc;
 }
 
@@ -499,7 +500,7 @@ __wterl_message_handler(WT_EVENT_HANDLER *handler, const char *message)
     ErlNifPid *to_pid;
     int rc = 0;
 
-    enif_mutex_lock(eh->message_mutex);
+    pthread_mutex_lock(&eh->message_mutex);
     msg_env = eh->msg_env_message;
     to_pid = &eh->to_pid;
     if (msg_env) {
@@ -512,7 +513,7 @@ __wterl_message_handler(WT_EVENT_HANDLER *handler, const char *message)
     } else {
         rc = (printf("%s\n", message) >= 0 ? 0 : EIO);
     }
-    enif_mutex_unlock(eh->message_mutex);
+    pthread_mutex_unlock(&eh->message_mutex);
     return rc;
 }
 
@@ -536,7 +537,7 @@ __wterl_progress_handler(WT_EVENT_HANDLER *handler, const char *operation, uint6
     ErlNifPid *to_pid;
     int rc = 0;
 
-    enif_mutex_lock(eh->progress_mutex);
+    pthread_mutex_lock(&eh->progress_mutex);
     msg_env = eh->msg_env_progress;
     to_pid = &eh->to_pid;
     if (msg_env) {
@@ -551,7 +552,7 @@ __wterl_progress_handler(WT_EVENT_HANDLER *handler, const char *operation, uint6
     } else {
         rc = (printf("[%llu] %s\n", PRIuint64(counter), operation) >= 0 ? 0 : EIO);
     }
-    enif_mutex_unlock(eh->progress_mutex);
+    pthread_mutex_unlock(&eh->progress_mutex);
     return rc;
 }
 
@@ -637,7 +638,7 @@ ASYNC_NIF_DECL(
           return;
       }
       if (session_config.size > 1) {
-          char *sc = enif_alloc(session_config.size);
+          char *sc = malloc(session_config.size);
           if (!sc) {
               enif_release_resource(conn_handle);
               ASYNC_NIF_REPLY(__strerror_term(env, ENOMEM));
@@ -648,8 +649,8 @@ ASYNC_NIF_DECL(
       } else {
           conn_handle->session_config = NULL;
       }
-      conn_handle->cache_mutex = enif_mutex_create("conn_handle");
-      enif_mutex_lock(conn_handle->cache_mutex);
+      pthread_mutex_init(&conn_handle->cache_mutex, 0);
+      pthread_mutex_lock(&conn_handle->cache_mutex);
       conn_handle->conn = conn;
       ERL_NIF_TERM result = enif_make_resource(env, conn_handle);
 
@@ -658,7 +659,7 @@ ASYNC_NIF_DECL(
       conn_handle->cache_size = 0;
 
       enif_release_resource(conn_handle);
-      enif_mutex_unlock(conn_handle->cache_mutex);
+      pthread_mutex_unlock(&conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(enif_make_tuple2(env, ATOM_OK, result));
     }
     else
@@ -695,16 +696,16 @@ ASYNC_NIF_DECL(
   { // work
 
     /* Free up the shared sessions and cursors. */
-    enif_mutex_lock(args->conn_handle->cache_mutex);
+    pthread_mutex_lock(&args->conn_handle->cache_mutex);
     __close_all_sessions(args->conn_handle);
     if (args->conn_handle->session_config) {
-        enif_free((char *)args->conn_handle->session_config);
+        free((char *)args->conn_handle->session_config);
         args->conn_handle->session_config = NULL;
     }
     WT_CONNECTION* conn = args->conn_handle->conn;
     int rc = conn->close(conn, NULL);
-    enif_mutex_unlock(args->conn_handle->cache_mutex);
-    enif_mutex_destroy(args->conn_handle->cache_mutex);
+    pthread_mutex_unlock(&args->conn_handle->cache_mutex);
+    pthread_mutex_destroy(&args->conn_handle->cache_mutex);
     memset(args->conn_handle, 0, sizeof(WterlConnHandle));
 
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
@@ -800,12 +801,12 @@ ASYNC_NIF_DECL(
   { // work
 
     /* This call requires that there be no open cursors referencing the object. */
-    enif_mutex_lock(args->conn_handle->cache_mutex);
+    pthread_mutex_lock(&args->conn_handle->cache_mutex);
     __close_cursors_on(args->conn_handle, args->uri);
 
     ErlNifBinary config;
     if (!enif_inspect_binary(env, args->config, &config)) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(enif_make_badarg(env));
       return;
     }
@@ -817,7 +818,7 @@ ASYNC_NIF_DECL(
     WT_SESSION *session = NULL;
     int rc = conn->open_session(conn, NULL, args->conn_handle->session_config, &session);
     if (rc != 0) {
-        enif_mutex_unlock(args->conn_handle->cache_mutex);
+        pthread_mutex_unlock(&args->conn_handle->cache_mutex);
         ASYNC_NIF_REPLY(__strerror_term(env, rc));
         return;
     }
@@ -827,7 +828,7 @@ ASYNC_NIF_DECL(
        this will result in EBUSY(16) "Device or resource busy". */
     rc = session->drop(session, args->uri, (const char*)config.data);
     (void)session->close(session, NULL);
-    enif_mutex_unlock(args->conn_handle->cache_mutex);
+    pthread_mutex_unlock(&args->conn_handle->cache_mutex);
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
   },
   { // post
@@ -867,12 +868,12 @@ ASYNC_NIF_DECL(
   { // work
 
     /* This call requires that there be no open cursors referencing the object. */
-    enif_mutex_lock(args->conn_handle->cache_mutex);
+    pthread_mutex_lock(&args->conn_handle->cache_mutex);
     __close_cursors_on(args->conn_handle, args->oldname);
 
     ErlNifBinary config;
     if (!enif_inspect_binary(env, args->config, &config)) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(enif_make_badarg(env));
       return;
     }
@@ -884,7 +885,7 @@ ASYNC_NIF_DECL(
     WT_SESSION *session = NULL;
     int rc = conn->open_session(conn, NULL, args->conn_handle->session_config, &session);
     if (rc != 0) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(__strerror_term(env, rc));
       return;
     }
@@ -895,7 +896,7 @@ ASYNC_NIF_DECL(
        this will result in EBUSY(16) "Device or resource busy". */
     rc = session->rename(session, args->oldname, args->newname, (const char*)config.data);
     (void)session->close(session, NULL);
-    enif_mutex_unlock(args->conn_handle->cache_mutex);
+    pthread_mutex_unlock(&args->conn_handle->cache_mutex);
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
   },
   { // post
@@ -935,12 +936,12 @@ ASYNC_NIF_DECL(
   { // work
 
     /* This call requires that there be no open cursors referencing the object. */
-    enif_mutex_lock(args->conn_handle->cache_mutex);
+    pthread_mutex_lock(&args->conn_handle->cache_mutex);
     __close_cursors_on(args->conn_handle, args->uri);
 
     ErlNifBinary config;
     if (!enif_inspect_binary(env, args->config, &config)) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(enif_make_badarg(env));
       return;
     }
@@ -952,14 +953,14 @@ ASYNC_NIF_DECL(
     WT_SESSION *session = NULL;
     int rc = conn->open_session(conn, NULL, args->conn_handle->session_config, &session);
     if (rc != 0) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(__strerror_term(env, rc));
       return;
     }
 
     rc = session->salvage(session, args->uri, (const char*)config.data);
     (void)session->close(session, NULL);
-    enif_mutex_unlock(args->conn_handle->cache_mutex);
+    pthread_mutex_unlock(&args->conn_handle->cache_mutex);
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
   },
   { // post
@@ -1067,12 +1068,12 @@ ASYNC_NIF_DECL(
   { // work
 
     /* This call requires that there be no open cursors referencing the object. */
-    enif_mutex_lock(args->conn_handle->cache_mutex);
+    pthread_mutex_lock(&args->conn_handle->cache_mutex);
     __close_cursors_on(args->conn_handle, args->uri);
 
     ErlNifBinary config;
     if (!enif_inspect_binary(env, args->config, &config)) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(enif_make_badarg(env));
       return;
     }
@@ -1085,7 +1086,7 @@ ASYNC_NIF_DECL(
     WT_SESSION *session = NULL;
     int rc = conn->open_session(conn, NULL, args->conn_handle->session_config, &session);
     if (rc != 0) {
-        enif_mutex_unlock(args->conn_handle->cache_mutex);
+        pthread_mutex_unlock(&args->conn_handle->cache_mutex);
         ASYNC_NIF_REPLY(__strerror_term(env, rc));
         return;
     }
@@ -1100,7 +1101,7 @@ ASYNC_NIF_DECL(
        mess. */
     if (!args->from_first) {
         if (!enif_inspect_binary(env, args->start, &start_key)) {
-            enif_mutex_unlock(args->conn_handle->cache_mutex);
+            pthread_mutex_unlock(&args->conn_handle->cache_mutex);
             ASYNC_NIF_REPLY(enif_make_badarg(env));
             return;
         }
@@ -1108,7 +1109,7 @@ ASYNC_NIF_DECL(
     rc = session->open_cursor(session, args->uri, NULL, "raw", &start);
     if (rc != 0) {
         session->close(session, NULL);
-        enif_mutex_unlock(args->conn_handle->cache_mutex);
+        pthread_mutex_unlock(&args->conn_handle->cache_mutex);
         ASYNC_NIF_REPLY(__strerror_term(env, rc));
         return;
     }
@@ -1118,7 +1119,7 @@ ASYNC_NIF_DECL(
         if (rc != 0) {
             start->close(start);
             session->close(session, NULL);
-            enif_mutex_unlock(args->conn_handle->cache_mutex);
+            pthread_mutex_unlock(&args->conn_handle->cache_mutex);
             ASYNC_NIF_REPLY(__strerror_term(env, rc));
             return;
         }
@@ -1133,7 +1134,7 @@ ASYNC_NIF_DECL(
         if (!enif_inspect_binary(env, args->stop, &stop_key)) {
             start->close(start);
             session->close(session, NULL);
-            enif_mutex_unlock(args->conn_handle->cache_mutex);
+            pthread_mutex_unlock(&args->conn_handle->cache_mutex);
             ASYNC_NIF_REPLY(enif_make_badarg(env));
             return;
         }
@@ -1142,7 +1143,7 @@ ASYNC_NIF_DECL(
     if (rc != 0) {
         start->close(start);
         session->close(session, NULL);
-        enif_mutex_unlock(args->conn_handle->cache_mutex);
+        pthread_mutex_unlock(&args->conn_handle->cache_mutex);
         ASYNC_NIF_REPLY(__strerror_term(env, rc));
         return;
     }
@@ -1153,7 +1154,7 @@ ASYNC_NIF_DECL(
             start->close(start);
             stop->close(stop);
             session->close(session, NULL);
-            enif_mutex_unlock(args->conn_handle->cache_mutex);
+            pthread_mutex_unlock(&args->conn_handle->cache_mutex);
             ASYNC_NIF_REPLY(__strerror_term(env, rc));
             return;
         }
@@ -1171,7 +1172,7 @@ ASYNC_NIF_DECL(
     start->close(start);
     stop->close(stop);
     session->close(session, NULL);
-    enif_mutex_unlock(args->conn_handle->cache_mutex);
+    pthread_mutex_unlock(&args->conn_handle->cache_mutex);
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
   },
   { // post
@@ -1208,12 +1209,12 @@ ASYNC_NIF_DECL(
   { // work
 
     /* This call requires that there be no open cursors referencing the object. */
-    enif_mutex_lock(args->conn_handle->cache_mutex);
+    pthread_mutex_lock(&args->conn_handle->cache_mutex);
     __close_cursors_on(args->conn_handle, args->uri);
 
     ErlNifBinary config;
     if (!enif_inspect_binary(env, args->config, &config)) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(enif_make_badarg(env));
       return;
     }
@@ -1225,14 +1226,14 @@ ASYNC_NIF_DECL(
     WT_SESSION *session = NULL;
     int rc = conn->open_session(conn, NULL, args->conn_handle->session_config, &session);
     if (rc != 0) {
-        enif_mutex_unlock(args->conn_handle->cache_mutex);
+        pthread_mutex_unlock(&args->conn_handle->cache_mutex);
         ASYNC_NIF_REPLY(__strerror_term(env, rc));
         return;
     }
 
     rc = session->upgrade(session, args->uri, (const char*)config.data);
     (void)session->close(session, NULL);
-    enif_mutex_unlock(args->conn_handle->cache_mutex);
+    pthread_mutex_unlock(&args->conn_handle->cache_mutex);
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
   },
   { // post
@@ -1270,12 +1271,12 @@ ASYNC_NIF_DECL(
   { // work
 
     /* This call requires that there be no open cursors referencing the object. */
-    enif_mutex_lock(args->conn_handle->cache_mutex);
+    pthread_mutex_lock(&args->conn_handle->cache_mutex);
     __close_all_sessions(args->conn_handle);
 
     ErlNifBinary config;
     if (!enif_inspect_binary(env, args->config, &config)) {
-      enif_mutex_unlock(args->conn_handle->cache_mutex);
+      pthread_mutex_unlock(&args->conn_handle->cache_mutex);
       ASYNC_NIF_REPLY(enif_make_badarg(env));
       return;
     }
@@ -1287,14 +1288,14 @@ ASYNC_NIF_DECL(
     WT_SESSION *session = NULL;
     int rc = conn->open_session(conn, NULL, args->conn_handle->session_config, &session);
     if (rc != 0) {
-        enif_mutex_unlock(args->conn_handle->cache_mutex);
+        pthread_mutex_unlock(&args->conn_handle->cache_mutex);
         ASYNC_NIF_REPLY(__strerror_term(env, rc));
         return;
     }
 
     rc = session->verify(session, args->uri, (const char*)config.data);
     (void)session->close(session, NULL);
-    enif_mutex_unlock(args->conn_handle->cache_mutex);
+    pthread_mutex_unlock(&args->conn_handle->cache_mutex);
     ASYNC_NIF_REPLY(rc == 0 ? ATOM_OK : __strerror_term(env, rc));
   },
   { // post
@@ -2220,13 +2221,13 @@ static void __wterl_conn_dtor(ErlNifEnv* env, void* obj)
     UNUSED(env);
     WterlConnHandle *conn_handle = (WterlConnHandle *)obj;
 
-    if (conn_handle->cache_mutex) {
+    if (conn_handle->conn) {
         DPRINTF("conn_handle dtor free'ing (%p)", obj);
-        enif_mutex_lock(conn_handle->cache_mutex);
+        pthread_mutex_lock(&conn_handle->cache_mutex);
         __close_all_sessions(conn_handle);
         conn_handle->conn->close(conn_handle->conn, NULL);
-        enif_mutex_unlock(conn_handle->cache_mutex);
-        enif_mutex_destroy(conn_handle->cache_mutex);
+        pthread_mutex_unlock(&conn_handle->cache_mutex);
+        pthread_mutex_destroy(&conn_handle->cache_mutex);
     }
 }
 
@@ -2265,15 +2266,15 @@ on_load(ErlNifEnv *env, void **priv_data, ERL_NIF_TERM load_info)
     ATOM_WIREDTIGER_VSN = enif_make_atom(env, "wiredtiger_vsn");
     ATOM_MSG_PID = enif_make_atom(env, "message_pid");
 
-    struct wterl_priv_data *priv = enif_alloc(sizeof(struct wterl_priv_data));
+    struct wterl_priv_data *priv = malloc(sizeof(struct wterl_priv_data));
     if (!priv)
         return ENOMEM;
     memset(priv, 0, sizeof(struct wterl_priv_data));
 
     struct wterl_event_handlers *eh = &priv->eh;
-    eh->error_mutex = enif_mutex_create("error_mutex");
-    eh->message_mutex = enif_mutex_create("message_mutex");
-    eh->progress_mutex = enif_mutex_create("progress_mutex");
+    pthread_mutex_init(&eh->error_mutex, 0);
+    pthread_mutex_init(&eh->message_mutex, 0);
+    pthread_mutex_init(&eh->progress_mutex, 0);
 
     /* Process the load_info array of tuples, we expect:
        [{wterl_vsn, "a version string"},
@@ -2296,7 +2297,7 @@ on_load(ErlNifEnv *env, void **priv_data, ERL_NIF_TERM load_info)
     ASYNC_NIF_LOAD(wterl, priv->async_nif_priv);
     if (!priv->async_nif_priv) {
         memset(priv, 0, sizeof(struct wterl_priv_data));
-        enif_free(priv);
+        free(priv);
         return ENOMEM;
     }
     *priv_data = priv;
@@ -2331,9 +2332,9 @@ on_unload(ErlNifEnv *env, void *priv_data)
        is no chance that the event handler functions will be called so we can
        be sure that there won't be a race on eh.msg_env in the callback functions. */
     struct wterl_event_handlers *eh = &priv->eh;
-    enif_mutex_destroy(eh->error_mutex);
-    enif_mutex_destroy(eh->message_mutex);
-    enif_mutex_destroy(eh->progress_mutex);
+    pthread_mutex_destroy(&eh->error_mutex);
+    pthread_mutex_destroy(&eh->message_mutex);
+    pthread_mutex_destroy(&eh->progress_mutex);
     if (eh->msg_env_message)
         enif_free_env(eh->msg_env_message);
     if (eh->msg_env_error)
@@ -2342,7 +2343,7 @@ on_unload(ErlNifEnv *env, void *priv_data)
         enif_free_env(eh->msg_env_progress);
 
     memset(priv, 0, sizeof(struct wterl_priv_data));
-    enif_free(priv);
+    free(priv);
 
     priv_data = NULL;
 }