diff --git a/lua_cjson.c b/lua_cjson.c
index f1aa4ad..f9348e5 100644
--- a/lua_cjson.c
+++ b/lua_cjson.c
@@ -826,7 +826,8 @@ static void json_append_newline_and_indent(strbuf_t *json, json_config_t *cfg, i
 static void json_append_array(lua_State *l, json_config_t *cfg, int current_depth,
                               strbuf_t *json, int array_length, int raw)
 {
-    int comma, i, json_pos, err;
+    int comma, i, err;
+    size_t json_pos;
     int has_items = 0;
 
     strbuf_append_char(json, '[');
@@ -1024,7 +1025,8 @@ static int cmp_key_entries(const void *a, const void *b)
 static void json_append_object(lua_State *l, json_config_t *cfg,
                                int current_depth, strbuf_t *json)
 {
-    int comma, keytype, json_pos, err;
+    int comma, keytype, err;
+    size_t json_pos;
     int has_items = 0;
     keybuf_t *keybuf;
     key_entry_t key_entry;
diff --git a/strbuf.h b/strbuf.h
index d77e0f4..1f2cddc 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -64,7 +64,7 @@ static char *strbuf_string(strbuf_t *s, size_t *len);
 static void strbuf_ensure_empty_length(strbuf_t *s, size_t len);
 static char *strbuf_empty_ptr(strbuf_t *s);
 static void strbuf_extend_length(strbuf_t *s, size_t len);
-static void strbuf_set_length(strbuf_t *s, int len);
+static void strbuf_set_length(strbuf_t *s, size_t len);
 
 /* Update */
 static void strbuf_append_mem(strbuf_t *s, const char *c, size_t len);
@@ -101,7 +101,7 @@ static inline char *strbuf_empty_ptr(strbuf_t *s)
     return s->buf + s->length;
 }
 
-static inline void strbuf_set_length(strbuf_t *s, int len)
+static inline void strbuf_set_length(strbuf_t *s, size_t len)
 {
     s->length = len;
 }