diff --git a/R/filter_events.R b/R/filter_events.R
index 8d88dd2..e0c22c8 100644
--- a/R/filter_events.R
+++ b/R/filter_events.R
@@ -116,6 +116,24 @@ filter_events <- function(data, year = format(Sys.Date(), "%Y"),
          "information", call. = FALSE)
   }
   
+  if (!is.character(format)) {
+    stop("Argument 'format' must be a character", call. = FALSE)
+  }
+  
+  if (length(format) != 1) {
+    stop("Argument 'format' must be of length 1", call. = FALSE)
+  }
+  
+  if (!is.logical(weekend)) {
+    stop("Argument 'weekend' must be a logical ('TRUE' or 'FALSE')", 
+         call. = FALSE)
+  }
+  
+  if (length(weekend) != 1) {
+    stop("Argument 'weekend' must be a logical ('TRUE' or 'FALSE')", 
+         call. = FALSE)
+  }
+  
   
   ## Filter event dates ----
   
diff --git a/R/get_calendar.R b/R/get_calendar.R
index 940b121..4d0c0cd 100644
--- a/R/get_calendar.R
+++ b/R/get_calendar.R
@@ -81,6 +81,27 @@ get_calendar <- function(year = format(Sys.Date(), "%Y"),
          call. = FALSE)
   }
   
+  if (!is.logical(weekend)) {
+    stop("Argument 'weekend' must be a logical ('TRUE' or 'FALSE')", 
+         call. = FALSE)
+  }
+  
+  if (length(weekend) != 1) {
+    stop("Argument 'weekend' must be a logical ('TRUE' or 'FALSE')", 
+         call. = FALSE)
+  }
+  
+  if (!is.null(lang)) {
+    if (!is.character(lang)) {
+      stop("Argument 'lang' must be a character", call. = FALSE)
+    }
+    
+    if (length(lang) != 1) {
+      stop("Argument 'lang' must be of length 1", call. = FALSE)
+    }
+  }
+  
+  
   ## Switch to US locale ----
   
   lc_time    <- Sys.getlocale("LC_TIME")
diff --git a/R/get_holidays.R b/R/get_holidays.R
index c0b9415..8c47e1a 100644
--- a/R/get_holidays.R
+++ b/R/get_holidays.R
@@ -4,7 +4,7 @@
 #' Scraps the site <https://www.timeanddate.com> to retrieve holidays data.
 #'
 #' @param country a `character` of length 1. The name of the country 
-#'   (e.g. `'France'`).
+#'   (e.g. `'France'`) to retrieve holidays for.
 #'
 #' @param year either an `integer` or a `character` of length 1. Must have 4 
 #'   characters (e.g. '2024' and not '24').
@@ -16,8 +16,10 @@
 #' @export
 #'
 #' @examples
+#' \dontrun{
 #' ## Get holidays for France in 2024 ----
 #' get_holidays("France", 2024)
+#' }
 
 get_holidays <- function(country, year) {
 
diff --git a/R/get_month_name.R b/R/get_month_name.R
index 2a9d7b5..c4b4741 100644
--- a/R/get_month_name.R
+++ b/R/get_month_name.R
@@ -41,6 +41,16 @@ get_month_name <- function(month, lang = NULL) {
     stop("Argument 'month' must be between 1 and 12", call. = FALSE)
   }
   
+  if (!is.null(lang)) {
+    if (!is.character(lang)) {
+      stop("Argument 'lang' must be a character", call. = FALSE)
+    }
+    
+    if (length(lang) != 1) {
+      stop("Argument 'lang' must be of length 1", call. = FALSE)
+    }
+  }
+  
   
   ## Switch locale ----
   
diff --git a/R/get_moon_phases.R b/R/get_moon_phases.R
index 56ce3e6..daffb00 100644
--- a/R/get_moon_phases.R
+++ b/R/get_moon_phases.R
@@ -1,25 +1,34 @@
 #' Get moon phases for a given year
 #'
 #' @description
-#' Scraps the site <https://www.timeanddate.com> to retrive moon phases data.
+#' Scraps the site <https://www.timeanddate.com> to retrieve moon phases data.
 #'
 #' @param year either an `integer` or a `character` of length 1. Must have 4 
 #'   characters (e.g. '2024' and not '24'). Default is the current year.
 #'   
 #' @return A `data.frame` with the following columns:
 #' - `new_moon`: the date of new moons (`YYYY-MM-DD`),
-#' - `full_moon`: the date of full moons (`integer`).
+#' - `full_moon`: the date of full moons (`YYYY-MM-DD`).
 #' 
 #' @export
 #'
 #' @examples
+#' \dontrun{
 #' ## Get moon phases for 2024 ----
 #' get_moon_phases(2024)
+#' }
 
 get_moon_phases <- function(year) {
   
+  ## Check args ----
+  
+  if (missing(year)) {
+    stop("Argument 'year' is required", call. = FALSE)
+  }
+  
   if (!is.character(year) && !is.numeric(year)) {
-    stop("Argument 'year' must either a character or an integer", call. = FALSE)
+    stop("Argument 'year' must be either a character or an integer", 
+         call. = FALSE)
   }
   
   if (length(year) > 1) {
diff --git a/R/get_weekday_name.R b/R/get_weekday_name.R
index 44dcb79..df8179d 100644
--- a/R/get_weekday_name.R
+++ b/R/get_weekday_name.R
@@ -54,6 +54,24 @@ get_weekday_name <- function(date, format = "%Y-%m-%d", lang = NULL) {
          "information", call. = FALSE)
   }
   
+  if (!is.character(format)) {
+    stop("Argument 'format' must be a character", call. = FALSE)
+  }
+  
+  if (length(format) != 1) {
+    stop("Argument 'format' must be of length 1", call. = FALSE)
+  }
+  
+  if (!is.null(lang)) {
+    if (!is.character(lang)) {
+      stop("Argument 'lang' must be a character", call. = FALSE)
+    }
+    
+    if (length(lang) != 1) {
+      stop("Argument 'lang' must be of length 1", call. = FALSE)
+    }
+  }
+  
   
   ## Switch locale ----
   
diff --git a/R/number_of_days.R b/R/number_of_days.R
index 36cacea..3ee46d7 100644
--- a/R/number_of_days.R
+++ b/R/number_of_days.R
@@ -28,6 +28,8 @@
 
 number_of_days <- function(date, format = "%Y-%m-%d") {
   
+  ## Check args ----
+  
   if (missing(date)) {
     stop("Argument 'date' is required", call. = FALSE)
   }
diff --git a/R/plot_calendar.R b/R/plot_calendar.R
index ade6cd3..e8e0d72 100644
--- a/R/plot_calendar.R
+++ b/R/plot_calendar.R
@@ -205,14 +205,43 @@ plot_calendar <- function(year = format(Sys.Date(), "%Y"),
   }
   
   
-  ## Create filename ----
+  ## Check moon ----
   
-  if (is.null(filename)) {
-    filename <- paste("calendar", year, month, sep = "-")
+  if (!is.logical(moon)) {
+    stop("Argument 'moon' must be a logical ('TRUE' or 'FALSE')", 
+         call. = FALSE)
+  }
+  
+  if (length(moon) != 1) {
+    stop("Argument 'moon' must be a logical ('TRUE' or 'FALSE')", 
+         call. = FALSE)
+  }
+  
+  
+  ## Check lang ----
+  
+  if (!is.null(lang)) {
+    if (!is.character(lang)) {
+      stop("Argument 'lang' must be a character", call. = FALSE)
+    }
+    
+    if (length(lang) != 1) {
+      stop("Argument 'lang' must be of length 1", call. = FALSE)
+    }
   }
   
-  filename <- paste0(filename, ".pdf")
-  filename <- gsub("\\.pdf\\.pdf", ".pdf", filename)
+  
+  ## Check country ----
+  
+  if (!is.null(country)) {
+    if (!is.character(country)) {
+      stop("Argument 'country' must be a character", call. = FALSE)
+    }
+    
+    if (length(country) != 1) {
+      stop("Argument 'country' must be of length 1", call. = FALSE)
+    }
+  }
   
   
   ## Get calendar data ----
@@ -220,6 +249,16 @@ plot_calendar <- function(year = format(Sys.Date(), "%Y"),
   calendar <- get_calendar(year, month, weekend, lang = lang)
   
   
+  ## Create file name ----
+  
+  if (is.null(filename)) {
+    filename <- paste("calendar", year, month, sep = "-")
+  }
+  
+  filename <- paste0(filename, ".pdf")
+  filename <- gsub("\\.pdf\\.pdf", ".pdf", filename)
+  
+  
   ## Create title ----
   
   if (is.null(title)) {
diff --git a/man/get_holidays.Rd b/man/get_holidays.Rd
index e2eab5a..24c29ff 100644
--- a/man/get_holidays.Rd
+++ b/man/get_holidays.Rd
@@ -8,7 +8,7 @@ get_holidays(country, year)
 }
 \arguments{
 \item{country}{a \code{character} of length 1. The name of the country
-(e.g. \code{'France'}).}
+(e.g. \code{'France'}) to retrieve holidays for.}
 
 \item{year}{either an \code{integer} or a \code{character} of length 1. Must have 4
 characters (e.g. '2024' and not '24').}
@@ -24,6 +24,8 @@ A \code{data.frame} with the following columns:
 Scraps the site \url{https://www.timeanddate.com} to retrieve holidays data.
 }
 \examples{
+\dontrun{
 ## Get holidays for France in 2024 ----
 get_holidays("France", 2024)
 }
+}
diff --git a/man/get_moon_phases.Rd b/man/get_moon_phases.Rd
index a670747..98ced14 100644
--- a/man/get_moon_phases.Rd
+++ b/man/get_moon_phases.Rd
@@ -14,13 +14,15 @@ characters (e.g. '2024' and not '24'). Default is the current year.}
 A \code{data.frame} with the following columns:
 \itemize{
 \item \code{new_moon}: the date of new moons (\code{YYYY-MM-DD}),
-\item \code{full_moon}: the date of full moons (\code{integer}).
+\item \code{full_moon}: the date of full moons (\code{YYYY-MM-DD}).
 }
 }
 \description{
-Scraps the site \url{https://www.timeanddate.com} to retrive moon phases data.
+Scraps the site \url{https://www.timeanddate.com} to retrieve moon phases data.
 }
 \examples{
+\dontrun{
 ## Get moon phases for 2024 ----
 get_moon_phases(2024)
 }
+}