diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0db451d1..43a1d523 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,7 +25,7 @@ set(INSTALL_INCLUDE_DIR include/magics CACHE PATH "Magics installation directory
 
 include(ecbuild_system NO_POLICY_SCOPE)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_C_STANDARD 99)
 
diff --git a/src/common/Polyline.cc b/src/common/Polyline.cc
index 76a117cf..836697da 100644
--- a/src/common/Polyline.cc
+++ b/src/common/Polyline.cc
@@ -107,7 +107,7 @@ struct SouthCleaner {
 
     bool operator()(PaperPoint& point) { return point.y_ < -89; }
 };
-struct LonFinder : std::unary_function<PaperPoint, bool> {
+struct LonFinder {
     LonFinder() {}
 
     bool operator()(PaperPoint& point) const { return (same(point.x_, -180.)); }