diff --git a/adaptive/learner/learner1D.py b/adaptive/learner/learner1D.py
index f8c7b6376..9aaae6639 100644
--- a/adaptive/learner/learner1D.py
+++ b/adaptive/learner/learner1D.py
@@ -654,7 +654,8 @@ def _get_data(self):
         return self.data
 
     def _set_data(self, data):
-        self.tell_many(*zip(*data.items()))
+        if data:
+            self.tell_many(*zip(*data.items()))
 
 
 def _fix_deepcopy(sorted_dict, x_scale):
diff --git a/adaptive/learner/learnerND.py b/adaptive/learner/learnerND.py
index 49488e7fe..02a98f45e 100644
--- a/adaptive/learner/learnerND.py
+++ b/adaptive/learner/learnerND.py
@@ -770,7 +770,8 @@ def _get_data(self):
         return self.data
 
     def _set_data(self, data):
-        self.tell_many(*zip(*data.items()))
+        if data:
+            self.tell_many(*zip(*data.items()))
 
     def _get_iso(self, level=0.0, which='surface'):
         if which == 'surface':