diff --git a/R/namespace.R b/R/namespace.R
index 1f2da792..7a834d29 100644
--- a/R/namespace.R
+++ b/R/namespace.R
@@ -208,7 +208,7 @@ roxy_tag_ns.roxy_tag_exportS3Method <- function(x, block, env) {
 
   if (identical(x$val, "")) {
     if (!inherits(obj, "s3method")) {
-      warn_roxy_tag(x, "must be used with an known S3 method")
+      warn_roxy_tag(x, "must be used with a known S3 method")
       return()
     }
 
diff --git a/tests/testthat/_snaps/namespace.md b/tests/testthat/_snaps/namespace.md
index ecd0e284..87ac4e57 100644
--- a/tests/testthat/_snaps/namespace.md
+++ b/tests/testthat/_snaps/namespace.md
@@ -3,7 +3,7 @@
     Code
       . <- roc_proc_text(namespace_roclet(), block)
     Message
-      x <text>:2: @exportS3Method must be used with an known S3 method.
+      x <text>:2: @exportS3Method must be used with a known S3 method.
 
 # @exportS3Method can extract class from generic