Index: src/library/stats/man/HoltWinters.Rd
===================================================================
--- src/library/stats/man/HoltWinters.Rd	(revision 74460)
+++ src/library/stats/man/HoltWinters.Rd	(working copy)
@@ -109,7 +109,7 @@
   C. C. Holt (1957)
   Forecasting seasonals and trends by exponentially weighted moving averages,
   \emph{ONR Research Memorandum, Carnegie Institute of Technology} \bold{52}.
-  (reprint at \url{http://dx.doi.org/10.1016/j.ijforecast.2003.09.015}).
+  (reprint at \url{https://doi.org/10.1016/j.ijforecast.2003.09.015}).
 
   P. R. Winters (1960).
   Forecasting sales by exponentially weighted moving averages.
Index: src/library/tools/R/toHTML.R
===================================================================
--- src/library/tools/R/toHTML.R	(revision 74460)
+++ src/library/tools/R/toHTML.R	(working copy)
@@ -310,12 +310,12 @@
                                                 urlify,
                                                 2L)
             s <- .gsub_with_transformed_matches("&lt;(DOI|doi):[[:space:]]*([^<[:space:]]+[[:alnum:]])&gt;",
-                                                "&lt;<a href=\"http://dx.doi.org/%s\">doi:\\2</a>&gt;",
+                                                "&lt;<a href=\"https://doi.org/%s\">doi:\\2</a>&gt;",
                                                 s,
                                                 urlify,
                                                 2L)
             s <- .gsub_with_transformed_matches("[^>\"](DOI|doi):[[:space:]]*([^<[:space:]]+[[:alnum:]])",
-                                                "&lt;<a href=\"http://dx.doi.org/%s\">doi:\\2</a>&gt;",
+                                                "&lt;<a href=\"https://doi.org/%s\">doi:\\2</a>&gt;",
                                                 s,
                                                 urlify,
                                                 2L)
Index: src/library/tools/R/utils.R
===================================================================
--- src/library/tools/R/utils.R	(revision 74460)
+++ src/library/tools/R/utils.R	(working copy)
@@ -600,7 +600,7 @@
 .canonicalize_doi <-
 function(x)
 {
-    x <- sub("^((doi|DOI):)?[[:space:]]*http://(dx[.])?doi[.]org/", "",
+    x <- sub("^((doi|DOI):)?[[:space:]]*https:?//(dx[.])?doi[.]org/", "",
              x)
     sub("^(doi|DOI):", "", x)
 }
