diff --git a/NAMESPACE b/NAMESPACE
index 90c1bfa..fcba66d 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -1,6 +1,5 @@
 # Generated by roxygen2: do not edit by hand
 
 export("%!%")
-export(slap)
 import(cli)
 import(rlang)
diff --git a/R/slap.R b/R/slap.R
index 822374c..b7fd8c6 100644
--- a/R/slap.R
+++ b/R/slap.R
@@ -24,13 +24,14 @@
 #' @name slap
 #' @export
 `%!%` <- function(expr, message) {
-  message <- enexpr(message)
-
   quo <- quo(
     withCallingHandlers(
       {{ expr }},
-      error = function(.__slap__.) {
-        message <- !!message
+      error = function(err) {
+        message <- {{ message }}
+        if (is.function(message)) {
+          message <- message(err)
+        }
 
         error_call <- env$.__error_call__.
         if (is.null(error_call)) {
@@ -40,7 +41,7 @@
           error_call <- NULL
         }
 
-        cli::cli_abort(message, parent = .__slap__., call = error_call)
+        cli::cli_abort(message, parent = err, call = error_call)
       }
     )
   )
@@ -48,8 +49,3 @@
   env <- caller_env()
   eval_tidy(quo, env = env, data = list(env = env))
 }
-
-#' @export
-slap <- function(error_call = current_env()) {
-  get(".__slap__.", caller_env()) %||% cli_abort("{.fn slap()} can only be used on the rhs of a `%!%`.", call = error_call)
-}