diff --git a/src/cache.h b/src/cache.h
index 2296b2cf..cc074bd3 100644
--- a/src/cache.h
+++ b/src/cache.h
@@ -1,12 +1,10 @@
 #pragma once
 
 #include <optional.h>
+
 #include <memory>
 #include <string>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 struct Config;
 struct IndexFile;
 
diff --git a/src/clang_cursor.h b/src/clang_cursor.h
index efbca7eb..19c09c42 100644
--- a/src/clang_cursor.h
+++ b/src/clang_cursor.h
@@ -1,14 +1,11 @@
 #pragma once
 
-#include <optional.h>
-
 #include <clang-c/Index.h>
+#include <optional.h>
 
 #include <string>
 #include <vector>
 
-using std::experimental::optional;
-
 class ClangType {
  public:
   ClangType();
diff --git a/src/clang_utils.h b/src/clang_utils.h
index 9dcaa246..d9b3668c 100644
--- a/src/clang_utils.h
+++ b/src/clang_utils.h
@@ -3,8 +3,8 @@
 #include "language_server_api.h"
 
 #include <clang-c/Index.h>
-
 #include <optional.h>
+
 #include <vector>
 
 using namespace std::experimental;
diff --git a/src/code_complete_cache.h b/src/code_complete_cache.h
index fca4b1e6..716b6704 100644
--- a/src/code_complete_cache.h
+++ b/src/code_complete_cache.h
@@ -6,9 +6,6 @@
 
 #include <mutex>
 
-using namespace std::experimental;
-using std::experimental::nullopt;
-
 // Cached completion information, so we can give fast completion results when
 // the user erases a character. vscode will resend the completion request if
 // that happens.
diff --git a/src/language_server_api.h b/src/language_server_api.h
index 2ada49b8..75cc2328 100644
--- a/src/language_server_api.h
+++ b/src/language_server_api.h
@@ -5,9 +5,9 @@
 #include "serializer.h"
 #include "utils.h"
 
-#include "optional.h"
-#include "variant.h"
+#include <optional.h>
 #include <rapidjson/writer.h>
+#include <variant.h>
 
 #include <algorithm>
 #include <iostream>
@@ -15,9 +15,6 @@
 #include <unordered_map>
 #include <unordered_set>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 /////////////////////////////////////////////////////////////////////////////
 /////////////////////////////////////////////////////////////////////////////
 /////////////////////////////////////////////////////////////////////////////
diff --git a/src/match.h b/src/match.h
index 26629d8e..6e7be8f9 100644
--- a/src/match.h
+++ b/src/match.h
@@ -6,9 +6,6 @@
 #include <string>
 #include <vector>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 struct Matcher {
   static optional<Matcher> Create(const std::string& search);
 
diff --git a/src/platform.h b/src/platform.h
index fe77172e..1210ec14 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -6,9 +6,6 @@
 #include <string>
 #include <vector>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 struct PlatformMutex {
   virtual ~PlatformMutex();
 };
diff --git a/src/project.h b/src/project.h
index 2619e435..3a9f6268 100644
--- a/src/project.h
+++ b/src/project.h
@@ -10,9 +10,6 @@
 #include <string>
 #include <vector>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 struct Project {
   struct Entry {
     std::string filename;
diff --git a/src/semantic_highlight_symbol_cache.h b/src/semantic_highlight_symbol_cache.h
index e18ba5f6..3a33f421 100644
--- a/src/semantic_highlight_symbol_cache.h
+++ b/src/semantic_highlight_symbol_cache.h
@@ -3,12 +3,11 @@
 #include "lru_cache.h"
 #include "query.h"
 
+#include <optional.h>
+
 #include <string>
 #include <unordered_map>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 // Caches symbols for a single file for semantic highlighting to provide
 // relatively stable ids. Only supports xxx files at a time.
 struct SemanticHighlightSymbolCache {
diff --git a/src/serializer.h b/src/serializer.h
index 08feb282..1f045968 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -1,18 +1,15 @@
 #pragma once
 
+#include <macro_map.h>
+#include <optional.h>
+#include <variant.h>
+#include <rapidjson/document.h>
+#include <rapidjson/prettywriter.h>
+
 #include <memory>
 #include <string>
 #include <vector>
 
-#include "macro_map.h"
-#include "optional.h"
-#include "variant.h"
-#include "rapidjson/document.h"
-#include "rapidjson/prettywriter.h"
-
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 using Reader = rapidjson::GenericValue<rapidjson::UTF8<>>;
 using Writer = rapidjson::Writer<rapidjson::StringBuffer>;
 struct IndexFile;
diff --git a/src/task.h b/src/task.h
index cce91906..04feeedb 100644
--- a/src/task.h
+++ b/src/task.h
@@ -9,9 +9,6 @@
 #include <unordered_map>
 #include <vector>
 
-using std::experimental::optional;
-using std::experimental::nullopt;
-
 enum class TaskThread {
   Indexer,
   QueryDb,
diff --git a/src/threaded_queue.h b/src/threaded_queue.h
index a14f6c80..7b6c1f1f 100644
--- a/src/threaded_queue.h
+++ b/src/threaded_queue.h
@@ -11,9 +11,6 @@
 #include <mutex>
 #include <queue>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 // TODO: cleanup includes.
 
 struct BaseThreadQueue {
diff --git a/src/timer.h b/src/timer.h
index 8c1856c1..dcc857a4 100644
--- a/src/timer.h
+++ b/src/timer.h
@@ -5,9 +5,6 @@
 #include <chrono>
 #include <string>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 struct Timer {
   using Clock = std::chrono::high_resolution_clock;
 
diff --git a/src/timestamp_manager.h b/src/timestamp_manager.h
index b652b448..5e1c499b 100644
--- a/src/timestamp_manager.h
+++ b/src/timestamp_manager.h
@@ -7,9 +7,6 @@
 #include <mutex>
 #include <unordered_map>
 
-using namespace std::experimental;
-using std::experimental::nullopt;
-
 // Caches timestamps of cc files so we can avoid a filesystem reads. This is
 // important for import perf, as during dependency checking the same files are
 // checked over and over again if they are common headers.
diff --git a/src/utils.h b/src/utils.h
index 60f170b8..08c97034 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -10,9 +10,6 @@
 #include <unordered_map>
 #include <vector>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 // Trim from start (in place)
 void TrimStartInPlace(std::string& s);
 // Trim from end (in place)
diff --git a/src/working_files.h b/src/working_files.h
index 7089c0be..42ec5260 100644
--- a/src/working_files.h
+++ b/src/working_files.h
@@ -9,9 +9,6 @@
 #include <mutex>
 #include <string>
 
-using std::experimental::nullopt;
-using std::experimental::optional;
-
 struct WorkingFile {
   int version = 0;
   std::string filename;