diff --git a/R/type.R b/R/type.R
index 656d9d8a3..0bb50dabf 100644
--- a/R/type.R
+++ b/R/type.R
@@ -94,11 +94,6 @@ format_type_sum <- function(x, width, ...) {
   UseMethod("format_type_sum")
 }
 
-# https://github.com/r-lib/pkgdown/issues/1540
-type_sum.accel <- function(x) {
-  I("kg m/s^2")
-}
-
 #' @export
 #' @rdname format_type_sum
 format_type_sum.default <- function(x, width, ...) {
diff --git a/R/zzz.R b/R/zzz.R
index 3fbf937c4..5e739e095 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -36,6 +36,13 @@
 #' @importFrom cli symbol
 NULL
 
+# https://github.com/r-lib/pkgdown/issues/1540
+if (Sys.getenv("IN_PKGDOWN") != "") {
+  type_sum.accel <- function(x) {
+    I("kg m/s^2")
+  }
+}
+
 # nolint start
 .onLoad <- function(libname, pkgname) {
   # nolint end