diff --git a/NAMESPACE b/NAMESPACE
index d20e3e4c..f46599aa 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -1,7 +1,5 @@
 # Generated by roxygen2: do not edit by hand
 
-S3method(as_ISOMetadata,emld)
-S3method(as_ISOMetadata,ncdf4)
 export(GMLAbstractCRS)
 export(GMLAbstractCoordinateOperation)
 export(GMLAbstractCoordinateSystem)
@@ -278,7 +276,6 @@ export(ISOUnlimitedInteger)
 export(ISOUsage)
 export(ISOVectorSpatialRepresentation)
 export(ISOVerticalExtent)
-export(as_ISOMetadata)
 export(geometaLogger)
 export(geometa_coverage)
 export(getGeometaOption)
diff --git a/R/geometa_mapping.R b/R/geometa_mapping.R
index 47244263..bd2f6b28 100644
--- a/R/geometa_mapping.R
+++ b/R/geometa_mapping.R
@@ -760,18 +760,8 @@ registerMappings <- function(x){
 
 #setters
 
-#' Convert foreign metadata object to an \code{\link{ISOMetadata}} object
-#'
-#' Convert foreign metadata object to an \code{\link{ISOMetadata}} object
-#' @param x object to convert
-#' @param ... further arguments
-#' @name as_ISOMetadata
-#' @export
-as_ISOMetadata = function(x, ...) UseMethod("as_ISOMetadata")
-
-#' @name as_ISOMetadata
-#' @export
-as_ISOMetadata.emld <- function(from){
+setOldClass("emld")
+setAs("emld", "ISOMetadata", function(from){
   if(!requireNamespace("EML", quietly = TRUE))
     stop("package EML required, please install it first")
   if(!requireNamespace("emld", quietly = TRUE))
@@ -781,36 +771,17 @@ as_ISOMetadata.emld <- function(from){
   out_md <- convert_metadata(in_from, from = "eml", to = "geometa", 
                              mappings = .geometa.mappings$rules, verbose = FALSE)
   return(out_md)
-}
+})
 
-#' @name as_ISOMetadata
-#' @export
-as_ISOMetadata.ncdf4 <- function(from){
+setOldClass("ncdf4")
+setAs("ncdf4", "ISOMetadata", function(from){
   if(!requireNamespace("ncdf4", quietly = TRUE))
     stop("package ncdf4 required, please install it first")
   out_md <- convert_metadata(from, from = "eml", to = "geometa", 
                              mappings = .geometa.mappings$rules, verbose = FALSE)
   return(out_md)
-}
-
-setOldClass("emld")
-#' @name as
-#' @rdname coerce-methods
-#' @aliases coerce,emld,ISOMetadata-method
-setAs("emld", "ISOMetadata", function(from) as_ISOMetadata(from))
-
-
-
-setOldClass("ncdf4")
-#' @name as
-#' @rdname coerce-methods
-#' @aliases coerce,ncdf4,ISOMetadata-method
-setAs("ncdf4", "ISOMetadata", function(from) as_ISOMetadata(from))
-
+})
 
-#' @name as
-#' @rdname coerce-methods
-#' @aliases coerce,ISOMetadata,emld-method
 setAs("ISOMetadata", "emld", function(from){
   if(!requireNamespace("EML", quietly = TRUE))
     stop("package EML required, please install it first")
diff --git a/man/as_ISOMetadata.Rd b/man/as_ISOMetadata.Rd
deleted file mode 100644
index 87f945d9..00000000
--- a/man/as_ISOMetadata.Rd
+++ /dev/null
@@ -1,22 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/geometa_mapping.R
-\name{as_ISOMetadata}
-\alias{as_ISOMetadata}
-\alias{as_ISOMetadata.emld}
-\alias{as_ISOMetadata.ncdf4}
-\title{Convert foreign metadata object to an \code{\link{ISOMetadata}} object}
-\usage{
-as_ISOMetadata(x, ...)
-
-\method{as_ISOMetadata}{emld}(from)
-
-\method{as_ISOMetadata}{ncdf4}(from)
-}
-\arguments{
-\item{x}{object to convert}
-
-\item{...}{further arguments}
-}
-\description{
-Convert foreign metadata object to an \code{\link{ISOMetadata}} object
-}