diff --git a/date.h b/date.h
index c527f56..f88e74c 100644
--- a/date.h
+++ b/date.h
@@ -3,7 +3,7 @@
 
 // The MIT License (MIT)
 // 
-// Copyright (c) 2015 Howard Hinnant
+// Copyright (c) 2015, 2016 Howard Hinnant
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -989,6 +989,13 @@ ceil(const std::chrono::time_point<Clock, FromDuration>& tp)
     return time_point<Clock, To>{ceil<To>(tp.time_since_epoch())};
 }
 
+#else  // _MSC_FULL_VER < 190023918
+
+using std::chrono::floor;
+using std::chrono::ceil;
+using std::chrono::round;
+using std::chrono::abs;
+
 #endif  // _MSC_FULL_VER < 190023918
 
 // trunc towards zero
@@ -3578,7 +3585,8 @@ public:
         os << std::abs(t.sub_s_.count()) * scale::num / scale::den;
 #else  // __cplusplus >= 201402
         // inefficient sub-optimal run-time mess, but gets the job done
-        const unsigned long long cl10 = std::ceil(log10(Period::den));
+        const unsigned long long cl10 =
+            static_cast<unsigned long long>(std::ceil(log10(Period::den)));
         const auto p10 = std::pow(10., cl10);
         os.width(cl10);
         os << static_cast<unsigned long long>(std::abs(t.sub_s_.count())
diff --git a/tz.h b/tz.h
index db97ac3..46e6386 100644
--- a/tz.h
+++ b/tz.h
@@ -85,6 +85,10 @@ static_assert(HAS_REMOTE_API == 0 ? AUTO_DOWNLOAD == 0 : true,
 #include <type_traits>
 #include <utility>
 #include <vector>
+#if LAZY_INIT
+#  include <memory>
+#  include <mutex>
+#endif
 
 namespace date
 {
@@ -738,7 +742,7 @@ format(const std::locale& loc, std::string format,
 
     using namespace std;
     using namespace std::chrono;
-    for (auto i = 0; i < format.size(); ++i)
+    for (std::size_t i = 0; i < format.size(); ++i)
     {
         if (format[i] == '%' && i < format.size()-1)
         {