diff --git a/jedi/evaluate/iterable.py b/jedi/evaluate/iterable.py
index aba6149e..7037903e 100644
--- a/jedi/evaluate/iterable.py
+++ b/jedi/evaluate/iterable.py
@@ -513,7 +513,9 @@ def _check_array_additions(evaluator, compare_array, module, is_list):
             # Is an Instance with an
             # Arguments([AlreadyEvaluated([ArrayInstance])]) inside
             # Yeah... I know... It's complicated ;-)
-            node = list(element.var_args.argument_node[0])[0].var_args
+            node = list(element.var_args.argument_node[0])[0].var_args.trailer
+        if isinstance(node, er.InstanceElement):
+            return node
         return node.get_parent_until(er.FunctionExecution)
 
     temp_param_add, settings.dynamic_params_for_other_modules = \
@@ -543,11 +545,6 @@ def _check_array_additions(evaluator, compare_array, module, is_list):
                         # improves Jedi's speed for array lookups, since we
                         # don't have to check the whole source tree anymore.
                         continue
-                # InstanceElements are special, because they don't get copied,
-                # but have this wrapper around them.
-                if isinstance(comp_arr_parent, er.InstanceElement):
-                    stmt = er.get_instance_el(comp_arr_parent.instance, stmt)
-
                 trailer = name.parent
                 power = trailer.parent
                 trailer_pos = power.children.index(trailer)
@@ -561,6 +558,11 @@ def _check_array_additions(evaluator, compare_array, module, is_list):
                             or execution_trailer.children[1] == ')':
                         continue
                 power = helpers.call_of_name(name, cut_own_trailer=True)
+                # InstanceElements are special, because they don't get copied,
+                # but have this wrapper around them.
+                if isinstance(comp_arr_parent, er.InstanceElement):
+                    power = er.get_instance_el(evaluator, comp_arr_parent.instance, power)
+
                 if evaluator.recursion_detector.push_stmt(power):
                     # Check for recursion. Possible by using 'extend' in
                     # combination with function calls.
diff --git a/jedi/evaluate/param.py b/jedi/evaluate/param.py
index d42b763d..dda803ea 100644
--- a/jedi/evaluate/param.py
+++ b/jedi/evaluate/param.py
@@ -23,7 +23,7 @@ class Arguments(pr.Base):
         """
         self.argument_node = argument_node
         self._evaluator = evaluator
-        self._trailer = trailer  # Can be None, e.g. in a class definition.
+        self.trailer = trailer  # Can be None, e.g. in a class definition.
 
     def _split(self):
         if isinstance(self.argument_node, (tuple, list)):
@@ -44,7 +44,7 @@ class Arguments(pr.Base):
                     yield 0, child
 
     def get_parent_until(self, *args, **kwargs):
-        return self._trailer.get_parent_until(*args, **kwargs)
+        return self.trailer.get_parent_until(*args, **kwargs)
 
     def as_tuple(self):
         for stars, argument in self._split():
@@ -126,7 +126,7 @@ class Arguments(pr.Base):
 
     def scope(self):
         # Returns the scope in which the arguments are used.
-        return (self._trailer or self.argument_node).get_parent_until(pr.IsScope)
+        return (self.trailer or self.argument_node).get_parent_until(pr.IsScope)
 
     def eval_args(self):
         # TODO this method doesn't work with named args and a lot of other
diff --git a/test/completion/dynamic_arrays.py b/test/completion/dynamic_arrays.py
index eb7781b8..19cb920f 100644
--- a/test/completion/dynamic_arrays.py
+++ b/test/completion/dynamic_arrays.py
@@ -242,13 +242,20 @@ class C():
         a[0]
         return a
 
-    def class_arr(self, el):
+    def literal_arr(self, el):
         self.a = []
         self.a.append(el)
         #? int()
         self.a[0]
         return self.a
 
+    def list_arr(self, el):
+        self.b = list([])
+        self.b.append(el)
+        #? float()
+        self.b[0]
+        return self.b
+
 #? int()
 C().blub(1)[0]
 #? float()
@@ -257,7 +264,12 @@ C().blub2(1)[0]
 #? int()
 C().a[0]
 #? int()
-C().class_arr(1)[0]
+C().literal_arr(1)[0]
+
+#? float()
+C().b[0]
+#? float()
+C().list_arr(1.0)[0]
 
 # -----------------
 # array recursions