diff --git a/NEWS.md b/NEWS.md
index 4db61489c..1f625ad74 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -2,6 +2,8 @@
 
 * `navset_card_pills()`, `navset_card_underline()`, `navset_card_tabs()` fixed to now respect header/footer arguments (@tanho63, #1024) 
 
+* `bs_themer()` fixed to prevent NULL values from crashing themer, fix #1111. (@meztez, #1112).
+
 # bslib 0.8.0
 
 ## Breaking changes
diff --git a/R/bs-theme-preview.R b/R/bs-theme-preview.R
index 86d34a9a0..20c49f3b3 100644
--- a/R/bs-theme-preview.R
+++ b/R/bs-theme-preview.R
@@ -411,7 +411,7 @@ bs_themer <- function(gfonts = TRUE, gfonts_update = FALSE) {
     # Validate that `vals` is a simple list, containing atomic elements,
     # that are all named
     if (!identical(class(vals), "list") ||
-        !all(vapply(vals, is.atomic, logical(1))) ||
+        !all(vapply(vals, function(x) {is.atomic(x) || is.null(x)}, logical(1))) ||
         is.null(names(vals)) ||
         !isTRUE(all(nzchar(names(vals), keepNA = TRUE)))) {
       warning(call. = FALSE,