diff --git a/formtools/wizard/storage/base.py b/formtools/wizard/storage/base.py
index aafc833..2e59679 100644
--- a/formtools/wizard/storage/base.py
+++ b/formtools/wizard/storage/base.py
@@ -69,7 +69,9 @@ class BaseStorage(object):
         wizard_files = self.data[self.step_files_key].get(step, {})
 
         if wizard_files and not self.file_storage:
-            raise NoFileStorageConfigured
+            raise NoFileStorageConfigured(
+                    "You need to define 'file_storage' in your "
+                    "wizard view in order to handle file uploads.")
 
         files = {}
         for field, field_dict in six.iteritems(wizard_files):
@@ -81,7 +83,9 @@ class BaseStorage(object):
 
     def set_step_files(self, step, files):
         if files and not self.file_storage:
-            raise NoFileStorageConfigured
+            raise NoFileStorageConfigured(
+                    "You need to define 'file_storage' in your "
+                    "wizard view in order to handle file uploads.")
 
         if step not in self.data[self.step_files_key]:
             self.data[self.step_files_key][step] = {}
diff --git a/formtools/wizard/views.py b/formtools/wizard/views.py
index ea41e86..5b45267 100644
--- a/formtools/wizard/views.py
+++ b/formtools/wizard/views.py
@@ -174,7 +174,9 @@ class WizardView(TemplateView):
             for field in six.itervalues(form.base_fields):
                 if (isinstance(field, forms.FileField) and
                         not hasattr(cls, 'file_storage')):
-                    raise NoFileStorageConfigured
+                    raise NoFileStorageConfigured(
+                            "You need to define 'file_storage' in your "
+                            "wizard view in order to handle file uploads.")
 
         # build the kwargs for the wizardview instances
         kwargs['form_list'] = init_form_list
@@ -436,8 +438,8 @@ class WizardView(TemplateView):
     def get_all_cleaned_data(self):
         """
         Returns a merged dictionary of all step cleaned_data dictionaries.
-        If a step contains a `FormSet`, the key will be prefixed with formset
-        and contain a list of the formset cleaned_data dictionaries.
+        If a step contains a `FormSet`, the key will be prefixed with
+        'formset-' and contain a list of the formset cleaned_data dictionaries.
         """
         cleaned_data = {}
         for form_key in self.get_form_list():
@@ -458,8 +460,8 @@ class WizardView(TemplateView):
     def get_cleaned_data_for_step(self, step):
         """
         Returns the cleaned data for a given `step`. Before returning the
-        cleaned data, the stored values are being revalidated through the
-        form. If the data doesn't validate, None will be returned.
+        cleaned data, the stored values are revalidated through the form.
+        If the data doesn't validate, None will be returned.
         """
         if step in self.form_list:
             form_obj = self.get_form(step=step,