diff --git a/_output.yaml b/_output.yaml
index a00027c..3cd1993 100644
--- a/_output.yaml
+++ b/_output.yaml
@@ -14,7 +14,7 @@ bookdown::gitbook:
       before: |
         <li><strong><a href="./">R for Data Science</a></strong></li>
     edit:
-      link: https://github.com/hadley/r4ds/edit/master/%s
+      link: https://github.com/hadley/r4ds/edit/main/%s
       text: "Edit"
     sharing: no
   css: r4ds.css
diff --git a/rmarkdown.Rmd b/rmarkdown.Rmd
index 2adfd31..2104e66 100644
--- a/rmarkdown.Rmd
+++ b/rmarkdown.Rmd
@@ -128,7 +128,7 @@ If you forget, you can get to a handy reference sheet with *Help \> Markdown Qui
     b.  Add a horizontal rule.
     c.  Add a block quote.
 
-3.  Copy and paste the contents of `diamond-sizes.Rmd` from <https://github.com/hadley/r4ds/tree/master/rmarkdown> in to a local R Markdown document.
+3.  Copy and paste the contents of `diamond-sizes.Rmd` from <https://github.com/hadley/r4ds/tree/main/rmarkdown> in to a local R Markdown document.
     Check that you can run it, then add text after the frequency polygon that describes its most striking features.
 
 ## Code chunks
@@ -343,7 +343,7 @@ comma(.12358124331)
 1.  Add a section that explores how diamond sizes vary by cut, colour, and clarity.
     Assume you're writing a report for someone who doesn't know R, and instead of setting `echo = FALSE` on each chunk, set a global option.
 
-2.  Download `diamond-sizes.Rmd` from <https://github.com/hadley/r4ds/tree/master/rmarkdown>.
+2.  Download `diamond-sizes.Rmd` from <https://github.com/hadley/r4ds/tree/main/rmarkdown>.
     Add a section that describes the largest 20 diamonds, including a table that displays their most important attributes.
 
 3.  Modify `diamonds-sizes.Rmd` to use `comma()` to produce nicely formatted output.