diff --git a/DESCRIPTION b/DESCRIPTION
index 3013c3f..53b6cb5 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: xfun
 Type: Package
 Title: Supporting Functions for Packages Maintained by 'Yihui Xie'
-Version: 0.46.4
+Version: 0.46.5
 Authors@R: c(
   person("Yihui", "Xie", role = c("aut", "cre", "cph"), email = "xie@yihui.name", comment = c(ORCID = "0000-0003-0645-5666")),
   person("Wush", "Wu", role = "ctb"),
diff --git a/R/utils.R b/R/utils.R
index b1d6357..155bc82 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -356,3 +356,8 @@ handle_error = function(
 
 # a shorthand for rm(list =, envir =)
 rm_vars = function(x, envir, ...) rm(list = x, envir = envir, ...)
+
+# for R < 3.3.x
+if (!exists('startsWith', baseenv(), inherits = TRUE)) startsWith = function(x, s) {
+  substring(x, 1, nchar(s)) == s
+}