diff --git a/NAMESPACE b/NAMESPACE
index 36a381584..4d59423a9 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -542,7 +542,7 @@ S3method(test_vuong,default)
 S3method(test_wald,ListNestedRegressions)
 S3method(test_wald,ListNonNestedRegressions)
 S3method(test_wald,default)
-export(as.dag.check_dag)
+export(as.dag)
 export(binned_residuals)
 export(check_autocorrelation)
 export(check_clusterstructure)
diff --git a/R/check_dag.R b/R/check_dag.R
index 207779407..215f5f89d 100644
--- a/R/check_dag.R
+++ b/R/check_dag.R
@@ -205,7 +205,10 @@ check_dag.default <- function(...,
 
 #' @rdname check_dag
 #' @export
-as.dag.check_dag <- function(x, ...) {
+as.dag <- function(x, ...) {
+  if (!inherits(x, "check_dag")) {
+    insight::format_error("Input is not of class `check_dag.")
+  }
   cat(as.character(x))
 }
 
diff --git a/man/check_dag.Rd b/man/check_dag.Rd
index 7e842dedb..b0039a142 100644
--- a/man/check_dag.Rd
+++ b/man/check_dag.Rd
@@ -2,7 +2,7 @@
 % Please edit documentation in R/check_dag.R
 \name{check_dag}
 \alias{check_dag}
-\alias{as.dag.check_dag}
+\alias{as.dag}
 \title{Check correct model adjustment for identifying causal effects}
 \usage{
 check_dag(
@@ -14,7 +14,7 @@ check_dag(
   effect = c("all", "total", "direct")
 )
 
-as.dag.check_dag(x, ...)
+as.dag(x, ...)
 }
 \arguments{
 \item{...}{One or more formulas, which are converted into \strong{dagitty} syntax.