diff --git a/vignettes/awesome_table_in_html.Rmd b/vignettes/awesome_table_in_html.Rmd
index 473ecf0..3af994c 100644
--- a/vignettes/awesome_table_in_html.Rmd
+++ b/vignettes/awesome_table_in_html.Rmd
@@ -452,4 +452,4 @@
 Since the structure of `kable` is relatively simple, it shouldn't be too difficult to convert HTML or LaTeX tables generated by other packages to a `kable` object and then use `kableExtra` to modify the outputs. If you are a package author, feel free to reach out to me and we can collaborate. 
 
 ## `tables`
-The latest version of [`tables`](https://cran.r-project.org/web/packages/tables/index.html) comes with a `toKable()` function, which is compatiable with functions in `kableExtra` (>=0.9.0).
+The latest version of [`tables`](https://CRAN.R-project.org/package=tables) comes with a `toKable()` function, which is compatiable with functions in `kableExtra` (>=0.9.0).
diff --git a/vignettes/awesome_table_in_pdf.Rmd b/vignettes/awesome_table_in_pdf.Rmd
index a5965db..5be9621 100644
--- a/vignettes/awesome_table_in_pdf.Rmd
+++ b/vignettes/awesome_table_in_pdf.Rmd
@@ -359,7 +359,7 @@
 ## Group rows via multi-row cell
 Function `group_rows` is great for showing simple structural information on rows but sometimes people may need to show structural information with multiple layers. When it happens, you may consider using `collapse_rows` instead, which will put repeating cells in columns into multi-row cells.  
 
-In LaTeX, `collapse_rows` adds some extra hlines to help differentiate groups. You can customize this behavior using the `latex_hline` argument. You can choose from `full` (default), `major` and `none`. Vertical alignment of cells is controlled by the `valign` option. You can choose from "top"(default), "middle" and "bottom".
+In LaTeX, `collapse_rows` adds some extra hlines to help differentiate groups. You can customize this behavior using the `latex_hline` argument. You can choose from `full` (default), `major` and `none`. Vertical alignment of cells is controlled by the `valign` option. You can choose from "top", "middle"(default) and "bottom". Be cautious that the vertical alignment option was only introduced in multirow in 2016. If you are using a legacy LaTeX distribution, you will run into trouble if you set `valign` to be either "top" or "bottom".
 
 ```{r}
 collapse_rows_dt <- data.frame(C1 = c(rep("a", 10), rep("b", 5)),
@@ -368,7 +368,7 @@
                  C4 = sample(c(0,1), 15, replace = TRUE))
 kable(collapse_rows_dt, "latex", booktabs = T, align = "c") %>%
   column_spec(1, bold=T) %>%
-  collapse_rows(columns = 1:2, latex_hline = "major", valign = "top")
+  collapse_rows(columns = 1:2, latex_hline = "major", valign = "middle")
 ```
 
 Right now, you can't automatically make striped rows based on collapsed rows but you can do it manually via the `extra_latex_after` option in `row_spec`. This feature is not officially supported. I'm only document it here if you want to give it a try. 
@@ -524,4 +524,4 @@
 Since the structure of `kable` is relatively simple, it shouldn't be too difficult to convert HTML or LaTeX tables generated by other packages to a `kable` object and then use `kableExtra` to modify the outputs. If you are a package author, feel free to reach out to me and we can collaborate. 
 
 ## `tables`
-The latest version of [`tables`](https://cran.r-project.org/web/packages/tables/index.html) comes with a `toKable()` function, which is compatiable with functions in `kableExtra` (>=0.9.0).
+The latest version of [`tables`](https://CRAN.R-project.org/package=tables) comes with a `toKable()` function, which is compatiable with functions in `kableExtra` (>=0.9.0).