diff --git a/lualib-src/lua-bson.c b/lualib-src/lua-bson.c
index 28414d51..29d6c70c 100644
--- a/lualib-src/lua-bson.c
+++ b/lualib-src/lua-bson.c
@@ -519,7 +519,10 @@ is_rawarray(lua_State *L) {
 	}
 	lua_Integer firstkey = lua_isinteger(L, -2) ? lua_tointeger(L, -2) : 0;
 	lua_pop(L, 2);
-	return firstkey > 0;
+	if (firstkey <= 1) {
+		return firstkey > 0;
+	}
+	return firstkey <= lua_rawlen(L, -1);
 }
 
 static void