diff --git a/R/demean.R b/R/demean.R
index 4393e1091..94bfc255f 100644
--- a/R/demean.R
+++ b/R/demean.R
@@ -205,7 +205,7 @@
 #' levels in descending order in the `by` argument. E.g.,
 #' `by = c("level4", "level3, "level2")` assumes a model like
 #' `y ~ x + (1|level4/level3/level2)`. An alternative notation for the
-#' `by`-argument would be `by = c("level4/level3/level2")`, similar to the
+#' `by`-argument would be `by = "level4/level3/level2"`, similar to the
 #' formula notation.
 #'
 #' @section Analysing panel data with mixed models using lme4:
diff --git a/man/demean.Rd b/man/demean.Rd
index cbf85dfa5..8a9a49308 100644
--- a/man/demean.Rd
+++ b/man/demean.Rd
@@ -273,7 +273,7 @@ nested designs, which is implemented in \code{demean()}. For nested designs, set
 levels in descending order in the \code{by} argument. E.g.,
 \verb{by = c("level4", "level3, "level2")} assumes a model like
 \code{y ~ x + (1|level4/level3/level2)}. An alternative notation for the
-\code{by}-argument would be \code{by = c("level4/level3/level2")}, similar to the
+\code{by}-argument would be \code{by = "level4/level3/level2"}, similar to the
 formula notation.
 }