diff --git a/DESCRIPTION b/DESCRIPTION
index 0b3a545e..9339aae5 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -47,7 +47,9 @@ Imports:
     sparseMatrixStats,
     stringr,
     SummarizedExperiment,
-    uwot
+    uwot,
+    methods,
+    utils
 Depends:
 Suggests:
     Cairo,
diff --git a/NAMESPACE b/NAMESPACE
index df517f94..a73cc258 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -171,4 +171,10 @@ import(data.table)
 importClassesFrom(GenomicRanges,GRanges)
 importFrom(GenomicRanges,GRanges)
 importFrom(Rcpp,sourceCpp)
+importFrom(methods,representation)
+importFrom(methods,setClass)
+importFrom(methods,setClassUnion)
+importFrom(methods,setMethod)
+importFrom(methods,setValidity)
+importFrom(utils,packageVersion)
 useDynLib(ArchR)
diff --git a/R/AllClasses.R b/R/AllClasses.R
index 64c0cd20..57545131 100644
--- a/R/AllClasses.R
+++ b/R/AllClasses.R
@@ -2,6 +2,8 @@
 #' @importFrom Rcpp sourceCpp
 #' @importClassesFrom GenomicRanges GRanges
 #' @importFrom GenomicRanges GRanges
+#' @importFrom methods setClassUnion setClass representation setValidity setMethod
+#' @importFrom utils packageVersion
 #' @import data.table
 NULL