diff --git a/DESCRIPTION b/DESCRIPTION
index 4a017a68..d3f912d8 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -45,7 +45,7 @@ Roxygen: list(markdown = TRUE, r6 = TRUE)
 RoxygenNote: 7.3.2
 Collate:
     'LearnerClust.R'
-    'aaa.R'
+    'zzz.R'
     'LearnerClustAffinityPropagation.R'
     'LearnerClustAgnes.R'
     'LearnerClustBICO.R'
@@ -82,4 +82,3 @@ Collate:
     'as_task_clust.R'
     'bibentries.R'
     'helper.R'
-    'zzz.R'
diff --git a/R/LearnerClustAffinityPropagation.R b/R/LearnerClustAffinityPropagation.R
index f0afd1c2..a6ed9013 100644
--- a/R/LearnerClustAffinityPropagation.R
+++ b/R/LearnerClustAffinityPropagation.R
@@ -81,5 +81,5 @@ LearnerClustAP = R6Class("LearnerClustAP",
   )
 )
 
-#' @include aaa.R
-learners[["clust.ap"]] = LearnerClustAP
+#' @include zzz.R
+register_learner("clust.ap", LearnerClustAP)
diff --git a/R/LearnerClustAgnes.R b/R/LearnerClustAgnes.R
index 5cdebea3..74643b0e 100644
--- a/R/LearnerClustAgnes.R
+++ b/R/LearnerClustAgnes.R
@@ -90,5 +90,5 @@ LearnerClustAgnes = R6Class("LearnerClustAgnes",
   )
 )
 
-#' @include aaa.R
-learners[["clust.agnes"]] = LearnerClustAgnes
+#' @include zzz.R
+register_learner("clust.agnes", LearnerClustAgnes)
diff --git a/R/LearnerClustBICO.R b/R/LearnerClustBICO.R
index 3f164d94..ed6318a0 100644
--- a/R/LearnerClustBICO.R
+++ b/R/LearnerClustBICO.R
@@ -61,5 +61,5 @@ LearnerClustBICO = R6Class("LearnerClustBICO",
   )
 )
 
-#' @include aaa.R
-learners[["clust.bico"]] = LearnerClustBICO
+#' @include zzz.R
+register_learner("clust.bico", LearnerClustBICO)
diff --git a/R/LearnerClustBIRCH.R b/R/LearnerClustBIRCH.R
index f42fee64..8fcdbbd1 100644
--- a/R/LearnerClustBIRCH.R
+++ b/R/LearnerClustBIRCH.R
@@ -62,5 +62,5 @@ LearnerClustBIRCH = R6Class("LearnerClustBIRCH",
   )
 )
 
-#' @include aaa.R
-learners[["clust.birch"]] = LearnerClustBIRCH
+#' @include zzz.R
+register_learner("clust.birch", LearnerClustBIRCH)
diff --git a/R/LearnerClustCMeans.R b/R/LearnerClustCMeans.R
index 763e77f6..dcb6d817 100644
--- a/R/LearnerClustCMeans.R
+++ b/R/LearnerClustCMeans.R
@@ -80,5 +80,5 @@ LearnerClustCMeans = R6Class("LearnerClustCMeans",
   )
 )
 
-#' @include aaa.R
-learners[["clust.cmeans"]] = LearnerClustCMeans
+#' @include zzz.R
+register_learner("clust.cmeans", LearnerClustCMeans)
diff --git a/R/LearnerClustCobweb.R b/R/LearnerClustCobweb.R
index 8d0ed0fd..81fefed6 100644
--- a/R/LearnerClustCobweb.R
+++ b/R/LearnerClustCobweb.R
@@ -58,5 +58,5 @@ LearnerClustCobweb = R6Class("LearnerClustCobweb",
   )
 )
 
-#' @include aaa.R
-learners[["clust.cobweb"]] = LearnerClustCobweb
+#' @include zzz.R
+register_learner("clust.cobweb", LearnerClustCobweb)
diff --git a/R/LearnerClustDBSCAN.R b/R/LearnerClustDBSCAN.R
index 7386485b..af360995 100644
--- a/R/LearnerClustDBSCAN.R
+++ b/R/LearnerClustDBSCAN.R
@@ -67,5 +67,5 @@ LearnerClustDBSCAN = R6Class("LearnerClustDBSCAN",
   )
 )
 
-#' @include aaa.R
-learners[["clust.dbscan"]] = LearnerClustDBSCAN
+#' @include zzz.R
+register_learner("clust.dbscan", LearnerClustDBSCAN)
diff --git a/R/LearnerClustDBSCANfpc.R b/R/LearnerClustDBSCANfpc.R
index 958acb5a..8f730a97 100644
--- a/R/LearnerClustDBSCANfpc.R
+++ b/R/LearnerClustDBSCANfpc.R
@@ -77,5 +77,5 @@ LearnerClustDBSCANfpc = R6Class("LearnerClustDBSCANfpc",
   )
 )
 
-#' @include aaa.R
-learners[["clust.dbscan_fpc"]] = LearnerClustDBSCANfpc
+#' @include zzz.R
+register_learner("clust.dbscan_fpc", LearnerClustDBSCANfpc)
diff --git a/R/LearnerClustDiana.R b/R/LearnerClustDiana.R
index 235b7105..859687b3 100644
--- a/R/LearnerClustDiana.R
+++ b/R/LearnerClustDiana.R
@@ -71,5 +71,5 @@ LearnerClustDiana = R6Class("LearnerClustDiana",
   )
 )
 
-#' @include aaa.R
-learners[["clust.diana"]] = LearnerClustDiana
+#' @include zzz.R
+register_learner("clust.diana", LearnerClustDiana)
diff --git a/R/LearnerClustEM.R b/R/LearnerClustEM.R
index d99cb105..858327ce 100644
--- a/R/LearnerClustEM.R
+++ b/R/LearnerClustEM.R
@@ -69,5 +69,5 @@ LearnerClustEM = R6Class("LearnerClustEM",
   )
 )
 
-#' @include aaa.R
-learners[["clust.em"]] = LearnerClustEM
+#' @include zzz.R
+register_learner("clust.em", LearnerClustEM)
diff --git a/R/LearnerClustFanny.R b/R/LearnerClustFanny.R
index 3d8dd1a7..b9135091 100644
--- a/R/LearnerClustFanny.R
+++ b/R/LearnerClustFanny.R
@@ -73,5 +73,5 @@ LearnerClustFanny = R6Class("LearnerClustFanny",
   )
 )
 
-#' @include aaa.R
-learners[["clust.fanny"]] = LearnerClustFanny
+#' @include zzz.R
+register_learner("clust.fanny", LearnerClustFanny)
diff --git a/R/LearnerClustFarthestFirst.R b/R/LearnerClustFarthestFirst.R
index 8dfc8d38..f9eb5243 100644
--- a/R/LearnerClustFarthestFirst.R
+++ b/R/LearnerClustFarthestFirst.R
@@ -59,5 +59,5 @@ LearnerClustFarthestFirst = R6Class("LearnerClustFF",
   )
 )
 
-#' @include aaa.R
-learners[["clust.ff"]] = LearnerClustFarthestFirst
+#' @include zzz.R
+register_learner("clust.ff", LearnerClustFarthestFirst)
diff --git a/R/LearnerClustFeatureless.R b/R/LearnerClustFeatureless.R
index 2c2c8b26..1b8321c0 100644
--- a/R/LearnerClustFeatureless.R
+++ b/R/LearnerClustFeatureless.R
@@ -80,5 +80,5 @@ LearnerClustFeatureless = R6Class("LearnerClustFeatureless",
   )
 )
 
-#' @include aaa.R
-learners[["clust.featureless"]] = LearnerClustFeatureless
+#' @include zzz.R
+register_learner("clust.featureless", LearnerClustFeatureless)
diff --git a/R/LearnerClustHDBSCAN.R b/R/LearnerClustHDBSCAN.R
index 37645301..447a534c 100644
--- a/R/LearnerClustHDBSCAN.R
+++ b/R/LearnerClustHDBSCAN.R
@@ -59,5 +59,5 @@ LearnerClustHDBSCAN = R6Class("LearnerClustHDBSCAN",
   )
 )
 
-#' @include aaa.R
-learners[["clust.hdbscan"]] = LearnerClustHDBSCAN
+#' @include zzz.R
+register_learner("clust.hdbscan", LearnerClustHDBSCAN)
diff --git a/R/LearnerClustHclust.R b/R/LearnerClustHclust.R
index 482b64ea..e5204d50 100644
--- a/R/LearnerClustHclust.R
+++ b/R/LearnerClustHclust.R
@@ -83,5 +83,5 @@ LearnerClustHclust = R6Class("LearnerClustHclust",
   )
 )
 
-#' @include aaa.R
-learners[["clust.hclust"]] = LearnerClustHclust
+#' @include zzz.R
+register_learner("clust.hclust", LearnerClustHclust)
diff --git a/R/LearnerClustKKMeans.R b/R/LearnerClustKKMeans.R
index 12f894c2..0e682a32 100644
--- a/R/LearnerClustKKMeans.R
+++ b/R/LearnerClustKKMeans.R
@@ -100,5 +100,5 @@ LearnerClustKKMeans = R6Class("LearnerClustKKMeans",
   )
 )
 
-#' @include aaa.R
-learners[["clust.kkmeans"]] = LearnerClustKKMeans
+#' @include zzz.R
+register_learner("clust.kkmeans", LearnerClustKKMeans)
diff --git a/R/LearnerClustKMeans.R b/R/LearnerClustKMeans.R
index 7147cbb3..2d152cfc 100644
--- a/R/LearnerClustKMeans.R
+++ b/R/LearnerClustKMeans.R
@@ -74,5 +74,5 @@ LearnerClustKMeans = R6Class("LearnerClustKMeans",
   )
 )
 
-#' @include aaa.R
-learners[["clust.kmeans"]] = LearnerClustKMeans
+#' @include zzz.R
+register_learner("clust.kmeans", LearnerClustKMeans)
diff --git a/R/LearnerClustMclust.R b/R/LearnerClustMclust.R
index dac8cd31..89720712 100644
--- a/R/LearnerClustMclust.R
+++ b/R/LearnerClustMclust.R
@@ -64,5 +64,5 @@ LearnerClustMclust = R6Class("LearnerClustMclust",
   )
 )
 
-#' @include aaa.R
-learners[["clust.mclust"]] = LearnerClustMclust
+#' @include zzz.R
+register_learner("clust.mclust", LearnerClustMclust)
diff --git a/R/LearnerClustMeanShift.R b/R/LearnerClustMeanShift.R
index ea158b25..d3ad6147 100644
--- a/R/LearnerClustMeanShift.R
+++ b/R/LearnerClustMeanShift.R
@@ -70,5 +70,5 @@ LearnerClustMeanShift = R6Class("LearnerClustMeanShift",
   )
 )
 
-#' @include aaa.R
-learners[["clust.meanshift"]] = LearnerClustMeanShift
+#' @include zzz.R
+register_learner("clust.meanshift", LearnerClustMeanShift)
diff --git a/R/LearnerClustMiniBatchKMeans.R b/R/LearnerClustMiniBatchKMeans.R
index d6a9178a..789edc0c 100644
--- a/R/LearnerClustMiniBatchKMeans.R
+++ b/R/LearnerClustMiniBatchKMeans.R
@@ -85,5 +85,5 @@ LearnerClustMiniBatchKMeans = R6Class("LearnerClustMiniBatchKMeans",
   )
 )
 
-#' @include aaa.R
-learners[["clust.MBatchKMeans"]] = LearnerClustMiniBatchKMeans
+#' @include zzz.R
+register_learner("clust.MBatchKMeans", LearnerClustMiniBatchKMeans)
diff --git a/R/LearnerClustOPTICS.R b/R/LearnerClustOPTICS.R
index e07dda2d..a91ac884 100644
--- a/R/LearnerClustOPTICS.R
+++ b/R/LearnerClustOPTICS.R
@@ -68,5 +68,5 @@ LearnerClustOPTICS = R6Class("LearnerClustOPTICS",
   )
 )
 
-#' @include aaa.R
-learners[["clust.optics"]] = LearnerClustOPTICS
+#' @include zzz.R
+register_learner("clust.optics", LearnerClustOPTICS)
diff --git a/R/LearnerClustPAM.R b/R/LearnerClustPAM.R
index f1f01bfe..19d521c2 100644
--- a/R/LearnerClustPAM.R
+++ b/R/LearnerClustPAM.R
@@ -78,5 +78,5 @@ LearnerClustPAM = R6Class("LearnerClustPAM",
   )
 )
 
-#' @include aaa.R
-learners[["clust.pam"]] = LearnerClustPAM
+#' @include zzz.R
+register_learner("clust.pam", LearnerClustPAM)
diff --git a/R/LearnerClustSimpleKMeans.R b/R/LearnerClustSimpleKMeans.R
index 6c82ab7e..217bbdcf 100644
--- a/R/LearnerClustSimpleKMeans.R
+++ b/R/LearnerClustSimpleKMeans.R
@@ -73,5 +73,5 @@ LearnerClustSimpleKMeans = R6Class("LearnerClustSimpleKMeans",
   )
 )
 
-#' @include aaa.R
-learners[["clust.SimpleKMeans"]] = LearnerClustSimpleKMeans
+#' @include zzz.R
+register_learner("clust.SimpleKMeans", LearnerClustSimpleKMeans)
diff --git a/R/LearnerClustXMeans.R b/R/LearnerClustXMeans.R
index 4f64f826..31f0416c 100644
--- a/R/LearnerClustXMeans.R
+++ b/R/LearnerClustXMeans.R
@@ -72,5 +72,5 @@ LearnerClustXMeans = R6Class("LearnerClustXMeans",
   )
 )
 
-#' @include aaa.R
-learners[["clust.xmeans"]] = LearnerClustXMeans
+#' @include zzz.R
+register_learner("clust.xmeans", LearnerClustXMeans)
diff --git a/R/TaskClust_ruspini.R b/R/TaskClust_ruspini.R
index eff69900..e7d5daf9 100644
--- a/R/TaskClust_ruspini.R
+++ b/R/TaskClust_ruspini.R
@@ -22,5 +22,5 @@ load_task_ruspini = function(id = "ruspini") {
   task
 }
 
-#' @include aaa.R
-tasks[["ruspini"]] = load_task_ruspini
+#' @include zzz.R
+register_task("ruspini", load_task_ruspini)
diff --git a/R/TaskClust_usarrest.R b/R/TaskClust_usarrest.R
index 48aa5eb3..c2b83815 100644
--- a/R/TaskClust_usarrest.R
+++ b/R/TaskClust_usarrest.R
@@ -25,5 +25,5 @@ load_task_usarrests = function(id = "usarrests") {
   task
 }
 
-#' @include aaa.R
-tasks[["usarrests"]] = load_task_usarrests
+#' @include zzz.R
+register_task("usarrests", load_task_usarrests)
diff --git a/R/aaa.R b/R/aaa.R
deleted file mode 100644
index 1b05fa0e..00000000
--- a/R/aaa.R
+++ /dev/null
@@ -1,2 +0,0 @@
-learners = list()
-tasks = list()
diff --git a/R/as_prediction_clust.R b/R/as_prediction_clust.R
index bc2ad087..c3992783 100644
--- a/R/as_prediction_clust.R
+++ b/R/as_prediction_clust.R
@@ -50,7 +50,7 @@ as_prediction_clust.data.frame = function(x, ...) { # nolint
 
   if (length(prob_cols)) {
     if (!all(startsWith(prob_cols, "prob."))) {
-      stopf("Table may only contain columns 'row_ids', 'partition' as well as columns prefixed with 'prob.' for class probabilities")
+      stopf("Table may only contain columns 'row_ids', 'partition' as well as columns prefixed with 'prob.' for class probabilities") # nolint
     }
     prob = as.matrix(x[, prob_cols, with = FALSE])
     colnames(prob) = substr(colnames(prob), 6L, nchar(colnames(prob)))
diff --git a/R/zzz.R b/R/zzz.R
index 42c598e9..0a91339a 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -1,70 +1,81 @@
+#' @import checkmate
 #' @import data.table
+#' @import mlr3
 #' @import mlr3misc
 #' @import paradox
-#' @import mlr3
-#' @import checkmate
 #' @importFrom R6 R6Class
 #' @importFrom clue cl_predict
-#' @importFrom fpc cluster.stats
 #' @importFrom cluster silhouette
+#' @importFrom fpc cluster.stats
 #' @importFrom stats model.frame terms predict runif dist
 "_PACKAGE"
 
+utils::globalVariables("type")
+
+mlr3cluster_tasks = new.env()
+mlr3cluster_learners = new.env()
+
+register_task = function(name, constructor) {
+  if (name %in% names(mlr3cluster_tasks)) stopf("task %s registered twice", name)
+  mlr3cluster_tasks[[name]] = constructor
+}
+
+register_learner = function(name, constructor) {
+  if (name %in% names(mlr3cluster_learners)) stopf("learner %s registered twice", name)
+  mlr3cluster_learners[[name]] = constructor
+}
+
 register_mlr3 = function() {
   # reflections
-  x = utils::getFromNamespace("mlr_reflections", ns = "mlr3")
-
-  # task
-  x$task_types = x$task_types[!"clust"]
-  x$task_types = setkeyv(rbind(x$task_types, rowwise_table(
+  mlr_reflections = utils::getFromNamespace("mlr_reflections", ns = "mlr3")
+  mlr_reflections$task_types = mlr_reflections$task_types[type != "clust"]
+  mlr_reflections$task_types = setkeyv(rbind(mlr_reflections$task_types, rowwise_table(
     ~type,    ~package,       ~task,        ~learner,       ~prediction,        ~prediction_data,       ~measure,
     "clust",  "mlr3cluster",  "TaskClust",  "LearnerClust", "PredictionClust",  "PredictionDataClust",  "MeasureClust"
   ), fill = TRUE), "type")
 
-  x$task_col_roles$clust = x$task_col_roles$regr
-  x$task_properties$clust = x$task_properties$regr
-  x$learner_properties$clust = c(
+  mlr_reflections$task_col_roles$clust = mlr_reflections$task_col_roles$regr
+  mlr_reflections$task_properties$clust = mlr_reflections$task_properties$regr
+  mlr_reflections$learner_properties$clust = c(
     "missings", "partitional", "hierarchical", "exclusive", "overlapping", "fuzzy", "complete", "partial", "density"
   )
-
-  # measure
-  x$measure_properties$clust = x$measure_properties$regr
-
-  # learner
-  x$learner_predict_types$clust = list(partition = "partition", prob = c("partition", "prob"))
-  x$default_measures$clust = "clust.dunn"
+  mlr_reflections$learner_predict_types$clust = list(partition = "partition", prob = c("partition", "prob"))
+  mlr_reflections$measure_properties$clust = mlr_reflections$measure_properties$regr
+  mlr_reflections$default_measures$clust = "clust.dunn"
 
   # tasks
-  x = utils::getFromNamespace("mlr_tasks", ns = "mlr3")
-  x$add("usarrests", load_task_usarrests)
-  x$add("ruspini", load_task_ruspini)
+  mlr_tasks = utils::getFromNamespace("mlr_tasks", ns = "mlr3")
+  iwalk(as.list(mlr3cluster_tasks), function(task, id) mlr_tasks$add(id, task))
 
   # learners
-  x = utils::getFromNamespace("mlr_learners", ns = "mlr3")
-  iwalk(learners, function(obj, nm) x$add(nm, obj))
+  mlr_learners = utils::getFromNamespace("mlr_learners", ns = "mlr3")
+  iwalk(as.list(mlr3cluster_learners), function(learner, id) mlr_learners$add(id, learner))
 
   # measures
-  x = utils::getFromNamespace("mlr_measures", ns = "mlr3")
-  x$add("clust.silhouette", MeasureClustSil, name = "silhouette", label = "Silhouette")
-  x$add("clust.dunn", MeasureClustFPC, name = "dunn", label = "Dunn")
-  x$add("clust.ch", MeasureClustFPC, name = "ch", label = "Calinski Harabasz")
-  x$add("clust.wss", MeasureClustFPC, name = "wss", label = "Within Sum of Squares")
+  mlr_measures = utils::getFromNamespace("mlr_measures", ns = "mlr3")
+  mlr_measures$add("clust.silhouette", MeasureClustSil, name = "silhouette", label = "Silhouette")
+  mlr_measures$add("clust.dunn", MeasureClustFPC, name = "dunn", label = "Dunn")
+  mlr_measures$add("clust.ch", MeasureClustFPC, name = "ch", label = "Calinski Harabasz")
+  mlr_measures$add("clust.wss", MeasureClustFPC, name = "wss", label = "Within Sum of Squares")
 }
 
 .onLoad = function(libname, pkgname) {
   backports::import(pkgname)
 
-  register_mlr3()
+  register_namespace_callback(pkgname, "mlr3", register_mlr3)
 }
 
 .onUnload = function(libpaths) { # nolint
-  mlr_learners = mlr3::mlr_learners
-  mlr_measures = mlr3::mlr_measures
-  mlr_tasks = mlr3::mlr_tasks
-
-  walk(names(learners), function(id) mlr_learners$remove(id))
+  walk(names(mlr3cluster_tasks), function(id) mlr_tasks$remove(id))
+  walk(names(mlr3cluster_learners), function(id) mlr_learners$remove(id))
   walk(names(measures), function(id) mlr_measures$remove(paste("clust", id, sep = ".")))
-  walk(names(tasks), function(id) mlr_tasks$remove(id))
+
+  mlr_reflections$task_types = mlr_reflections$task_types[type != "clust"]
+  reflections = c(
+    "measure_properties", "default_measures", "learner_properties",
+    "learner_predict_types",  "task_properties", "task_col_roles"
+  )
+  walk(reflections, function(x) mlr_reflections[[x]] = remove_named(mlr_reflections[[x]], "clust"))
 }
 
 leanify_package()
diff --git a/tests/testthat/helper.R b/tests/testthat/helper.R
index 3afe5708..d2568080 100644
--- a/tests/testthat/helper.R
+++ b/tests/testthat/helper.R
@@ -1,4 +1,4 @@
-library(testthat)
+library(checkmate)
 library(mlr3)
 library(mlr3cluster)
-library(checkmate)
+library(testthat)