diff --git a/src/TmxUtil.cpp b/src/TmxUtil.cpp
index 26993c7..184842d 100644
--- a/src/TmxUtil.cpp
+++ b/src/TmxUtil.cpp
@@ -46,13 +46,13 @@ namespace Tmx {
 
     // trim from start
     static inline std::string &ltrim(std::string &s) {
-        s.erase(s.begin(), std::find_if(s.begin(), s.end(), std::not1(std::ptr_fun<int, int>(std::isspace))));
+        s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](int c){ return !std::isspace(c); }));
         return s;
     }
 
     // trim from end
     static inline std::string &rtrim(std::string &s) {
-        s.erase(std::find_if(s.rbegin(), s.rend(), std::not1(std::ptr_fun<int, int>(std::isspace))).base(), s.end());
+        s.erase(std::find_if(s.rbegin(), s.rend(), [](int c){ return !std::isspace(c); }).base(), s.end());
         return s;
     }