diff --git a/src/main/actions_lua.c b/src/main/actions_lua.c
index b29d319..648d98c 100644
--- a/src/main/actions_lua.c
+++ b/src/main/actions_lua.c
@@ -38,6 +38,11 @@ static int lua_action_gc(lua_State *L) {
 int li_lua_push_action(liServer *srv, lua_State *L, liAction *a) {
 	liAction **pa;
 
+	if (NULL == a) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pa = (liAction**) lua_newuserdata(L, sizeof(liAction*));
 	*pa = a;
 
diff --git a/src/main/chunk_lua.c b/src/main/chunk_lua.c
index 342c0dc..fc31f7d 100644
--- a/src/main/chunk_lua.c
+++ b/src/main/chunk_lua.c
@@ -290,6 +290,11 @@ liChunk* li_lua_get_chunk(lua_State *L, int ndx) {
 int li_lua_push_chunk(lua_State *L, liChunk *c) {
 	liChunk **pc;
 
+	if (NULL == c) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pc = (liChunk**) lua_newuserdata(L, sizeof(liChunk*));
 	*pc = c;
 
@@ -316,6 +321,11 @@ liChunkQueue* li_lua_get_chunkqueue(lua_State *L, int ndx) {
 int li_lua_push_chunkqueue(lua_State *L, liChunkQueue *cq) {
 	liChunkQueue **pcq;
 
+	if (NULL == cq) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pcq = (liChunkQueue**) lua_newuserdata(L, sizeof(liChunkQueue*));
 	*pcq = cq;
 
diff --git a/src/main/condition_lua.c b/src/main/condition_lua.c
index 249bb92..2247a46 100644
--- a/src/main/condition_lua.c
+++ b/src/main/condition_lua.c
@@ -122,6 +122,11 @@ static void lua_push_condition_metatable(liServer *srv, lua_State *L) {
 int li_lua_push_condition(liServer *srv, lua_State *L, liCondition *c) {
 	liCondition **pc;
 
+	if (NULL == c) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pc = (liCondition**) lua_newuserdata(L, sizeof(liCondition*));
 	*pc = c;
 
diff --git a/src/main/environment_lua.c b/src/main/environment_lua.c
index faa49ca..5ba4e3c 100644
--- a/src/main/environment_lua.c
+++ b/src/main/environment_lua.c
@@ -139,6 +139,11 @@ liEnvironment* li_lua_get_environment(lua_State *L, int ndx) {
 int li_lua_push_environment(lua_State *L, liEnvironment *env) {
 	liEnvironment **penv;
 
+	if (NULL == env) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	penv = (liEnvironment**) lua_newuserdata(L, sizeof(liEnvironment*));
 	*penv = env;
 
diff --git a/src/main/filters_lua.c b/src/main/filters_lua.c
index fc30ad7..de712e9 100644
--- a/src/main/filters_lua.c
+++ b/src/main/filters_lua.c
@@ -137,6 +137,11 @@ liFilter* li_lua_get_filter(lua_State *L, int ndx) {
 int li_lua_push_filter(lua_State *L, liFilter *f) {
 	liFilter **pf;
 
+	if (NULL == f) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pf = (liFilter**) lua_newuserdata(L, sizeof(liFilter*));
 	*pf = f;
 
diff --git a/src/main/http_headers_lua.c b/src/main/http_headers_lua.c
index fe6658f..dc6e749 100644
--- a/src/main/http_headers_lua.c
+++ b/src/main/http_headers_lua.c
@@ -227,6 +227,11 @@ liHttpHeaders* li_lua_get_http_headers(lua_State *L, int ndx) {
 int li_lua_push_http_headers(lua_State *L, liHttpHeaders *headers) {
 	liHttpHeaders **pheaders;
 
+	if (NULL == headers) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pheaders = (liHttpHeaders**) lua_newuserdata(L, sizeof(liHttpHeaders*));
 	*pheaders = headers;
 
diff --git a/src/main/physical_lua.c b/src/main/physical_lua.c
index cc165e1..627327c 100644
--- a/src/main/physical_lua.c
+++ b/src/main/physical_lua.c
@@ -153,6 +153,11 @@ liPhysical* li_lua_get_physical(lua_State *L, int ndx) {
 int li_lua_push_physical(lua_State *L, liPhysical *phys) {
 	liPhysical **pphys;
 
+	if (NULL == phys) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pphys = (liPhysical**) lua_newuserdata(L, sizeof(liPhysical*));
 	*pphys = phys;
 
diff --git a/src/main/request_lua.c b/src/main/request_lua.c
index 2f8a6f1..6224ce1 100644
--- a/src/main/request_lua.c
+++ b/src/main/request_lua.c
@@ -309,6 +309,11 @@ liRequest* li_lua_get_request(lua_State *L, int ndx) {
 int li_lua_push_request(lua_State *L, liRequest *req) {
 	liRequest **preq;
 
+	if (NULL == req) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	preq = (liRequest**) lua_newuserdata(L, sizeof(liRequest*));
 	*preq = req;
 
@@ -335,6 +340,11 @@ liRequestUri* li_lua_get_requesturi(lua_State *L, int ndx) {
 int li_lua_push_requesturi(lua_State *L, liRequestUri *uri) {
 	liRequestUri **puri;
 
+	if (NULL == uri) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	puri = (liRequestUri**) lua_newuserdata(L, sizeof(liRequestUri*));
 	*puri = uri;
 
diff --git a/src/main/response_lua.c b/src/main/response_lua.c
index 6b11e2e..fc8627a 100644
--- a/src/main/response_lua.c
+++ b/src/main/response_lua.c
@@ -148,6 +148,11 @@ liResponse* li_lua_get_response(lua_State *L, int ndx) {
 int li_lua_push_response(lua_State *L, liResponse *resp) {
 	liResponse **presp;
 
+	if (NULL == resp) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	presp = (liResponse**) lua_newuserdata(L, sizeof(liResponse*));
 	*presp = resp;
 
diff --git a/src/main/stat_lua.c b/src/main/stat_lua.c
index 77facb0..05e1051 100644
--- a/src/main/stat_lua.c
+++ b/src/main/stat_lua.c
@@ -220,6 +220,11 @@ void li_lua_init_stat_mt(lua_State *L) {
 int li_lua_push_stat(lua_State *L, struct stat *st) {
 	struct stat *pst;
 
+	if (NULL == st) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pst = (struct stat*) lua_newuserdata(L, sizeof(struct stat));
 	*pst = *st;
 
diff --git a/src/main/subrequest_lua.c b/src/main/subrequest_lua.c
index 0eadc7f..272411e 100644
--- a/src/main/subrequest_lua.c
+++ b/src/main/subrequest_lua.c
@@ -182,6 +182,11 @@ static liSubrequest* li_lua_get_subrequest(lua_State *L, int ndx) {
 static int li_lua_push_subrequest(lua_State *L, liSubrequest *sr) {
 	liSubrequest **psr;
 
+	if (NULL == sr) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	psr = (liSubrequest**) lua_newuserdata(L, sizeof(liSubrequest*));
 	*psr = sr;
 
diff --git a/src/main/virtualrequest_lua.c b/src/main/virtualrequest_lua.c
index 0297cf9..1e55255 100644
--- a/src/main/virtualrequest_lua.c
+++ b/src/main/virtualrequest_lua.c
@@ -366,6 +366,11 @@ liVRequest* li_lua_get_vrequest(lua_State *L, int ndx) {
 int li_lua_push_vrequest(lua_State *L, liVRequest *vr) {
 	liVRequest **pvr;
 
+	if (NULL == vr) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pvr = (liVRequest**) lua_newuserdata(L, sizeof(liVRequest*));
 	*pvr = vr;
 
@@ -513,6 +518,11 @@ liConInfo* li_lua_get_coninfo(lua_State *L, int ndx) {
 int li_lua_push_coninfo(lua_State *L, liConInfo *coninfo) {
 	liConInfo **pconinfo;
 
+	if (NULL == coninfo) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pconinfo = (liConInfo**) lua_newuserdata(L, sizeof(liConInfo*));
 	*pconinfo = coninfo;
 
diff --git a/src/modules/mod_memcached.c b/src/modules/mod_memcached.c
index da4bc23..cc8575c 100644
--- a/src/modules/mod_memcached.c
+++ b/src/modules/mod_memcached.c
@@ -998,6 +998,11 @@ static int lua_memcached_con_gc(lua_State *L) {
 static int li_lua_push_memcached_con(lua_State *L, liMemcachedCon *con) {
 	liMemcachedCon **pcon;
 
+	if (NULL == con) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	pcon = (liMemcachedCon**) lua_newuserdata(L, sizeof(liMemcachedCon*));
 	*pcon = con;
 
@@ -1044,6 +1049,11 @@ static int lua_memcached_req_gc(lua_State *L) {
 static int li_lua_push_memcached_req(lua_State *L, mc_lua_request *req) {
 	mc_lua_request **preq;
 
+	if (NULL == req) {
+		lua_pushnil(L);
+		return 1;
+	}
+
 	preq = (mc_lua_request**) lua_newuserdata(L, sizeof(mc_lua_request*));
 	*preq = req;