diff --git a/R/method-introspect.R b/R/method-introspect.R
index 367ed01e..40e073e7 100644
--- a/R/method-introspect.R
+++ b/R/method-introspect.R
@@ -36,7 +36,7 @@
 #' try(method(bizarro, class = class_data.frame))
 #' try(method(bizarro, object = "x"))
 method <- function(generic, class = NULL, object = NULL) {
-  generic <- as_generic(generic)
+  check_is_S7(generic, S7_generic)
   dispatch <- as_dispatch(generic, class = class, object = object)
 
   method <- .Call(method_, generic, dispatch, environment(), FALSE)
@@ -78,7 +78,7 @@ method <- function(generic, class = NULL, object = NULL) {
 #'
 #' method_explain(add, list(foo2, foo2))
 method_explain <- function(generic, class = NULL, object = NULL) {
-  generic <- as_generic(generic)
+  check_is_S7(generic, S7_generic)
   dispatch <- as_dispatch(generic, class = class, object = object)
   dispatch <- lapply(dispatch, c, "ANY")
 
@@ -108,8 +108,6 @@ method_explain <- function(generic, class = NULL, object = NULL) {
 
 
 as_dispatch <- function(generic, class = NULL, object = NULL) {
-  check_is_S7(generic, S7_generic)
-
   if (!is.null(class) && is.null(object)) {
     signature <- as_signature(class, generic)
     is_union <- vlapply(signature, is_union)
diff --git a/tests/testthat/_snaps/method-introspect.md b/tests/testthat/_snaps/method-introspect.md
index f0eaef6c..dfd43387 100644
--- a/tests/testthat/_snaps/method-introspect.md
+++ b/tests/testthat/_snaps/method-introspect.md
@@ -4,7 +4,7 @@
       method(print, 1)
     Condition
       Error:
-      ! `generic` must be a <S7_generic>, not a S3<S7_S3_generic>
+      ! `generic` must be a <S7_generic>, not a <closure>
     Code
       foo <- new_generic("foo", "x")
       method(foo)