diff --git a/Makefile b/Makefile
index 4c697b2..3644e74 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ BUILDTYPE ?= Release
 PREFIX := /usr/local
 LDFLAGS := -lssl -lcrypto -lboost_system -lcpprest -pthread
 WARNING_FLAGS := -pedantic -Werror -Wall -Wextra -Weffc++ -Wundef -Wshadow -Wstrict-aliasing -Wswitch-enum -Wformat=2 -Wattributes -Woverloaded-virtual -Wnon-virtual-dtor -Wctor-dtor-privacy -Wold-style-cast -Wconversion -Wframe-larger-than=32768 -Wredundant-decls
-COMMON_FLAGS := -g -pthread -std=gnu++14 -fdiagnostics-show-option -fdiagnostics-generate-patch
+COMMON_FLAGS := -g -pthread -std=gnu++17 -fdiagnostics-show-option -fdiagnostics-generate-patch
 RELEASE_FLAGS := -O2 -DNDEBUG
 DEBUG_FLAGS := -O0 -DDEBUG -fno-inline-functions -fno-omit-frame-pointer
 
diff --git a/main.cc b/main.cc
index 81a9c0c..85be1a8 100644
--- a/main.cc
+++ b/main.cc
@@ -24,7 +24,6 @@
  */
 
 #include <pthread.h>
-#include <boost/optional.hpp>
 #include <cpprest/http_client.h>
 #include <bits/stdc++.h>
 
@@ -61,7 +60,7 @@ public:
 
   // Lookup the hostname in the cache and return the URL if present.
   // If the entry is present, it is moved to the head of the queue.
-  boost::optional<const string> get(const string &key)
+  std::optional<const string> get(const string &key)
   {
     auto location = map.find(key);
     if (location == map.end())