diff --git a/src/lceasy.c b/src/lceasy.c
index ad48022..4fc4c78 100644
--- a/src/lceasy.c
+++ b/src/lceasy.c
@@ -130,7 +130,7 @@ static int lcurl_easy_to_s(lua_State *L){
   return 1;
 }
 
-static int lcurl_easy_cleanup_storage(lua_State *L, lcurl_easy_t *p){
+static void lcurl_easy_cleanup_storage(lua_State *L, lcurl_easy_t *p){
   int i;
 
   if(p->storage != LUA_NOREF){
diff --git a/src/lcurl.c b/src/lcurl.c
index e70680d..95df0ff 100644
--- a/src/lcurl.c
+++ b/src/lcurl.c
@@ -230,6 +230,11 @@ static int push_upper(lua_State *L, const char *str){
   size_t i, n = strlen(str);
   char *ptr = (n < sizeof(buffer))?&buffer[0]:malloc(n + 1);
   if (!ptr) return 1;
+  if (n == 0) {
+    lua_pushlstring(L, "", 0);
+    if(ptr != &buffer[0]) free(ptr);
+    return 0;
+  }
   for(i = 0; i < n; ++i){
     if( (str[i] > 96 ) && (str[i] < 123) ) ptr[i] = str[i] - 'a' + 'A';
     else ptr[i] = str[i];