diff -Nru orig/RcppCCTZ/src/Makevars.ucrt patched/RcppCCTZ/src/Makevars.ucrt
--- orig/RcppCCTZ/src/Makevars.ucrt	1970-01-01 01:00:00.000000000 +0100
+++ patched/RcppCCTZ/src/Makevars.ucrt	2021-02-17 19:45:26.800362100 +0100
@@ -0,0 +1,6 @@
+
+## We want C++11 
+CXX_STD = CXX11
+
+PKG_CXXFLAGS = -I../inst/include -D_POSIX_THREAD_SAFE_FUNCTIONS
+