diff --git a/qutebrowser/utils/completion.py b/qutebrowser/utils/completion.py
index a70a7f898..da48586ae 100644
--- a/qutebrowser/utils/completion.py
+++ b/qutebrowser/utils/completion.py
@@ -276,6 +276,7 @@ class CompletionFilterModel(QSortFilterProxyModel):
     """Subclass of QSortFilterProxyModel with custom sorting/filtering."""
 
     _pattern = None
+    srcmodel = None
 
     def __init__(self, parent=None):
         super().__init__(parent)
@@ -286,6 +287,11 @@ class CompletionFilterModel(QSortFilterProxyModel):
         """Getter for pattern."""
         return self._pattern
 
+    def setsrc(self, model):
+        self.setSourceModel(model)
+        self.srcmodel = model
+        self.pattern = ''
+
     @pattern.setter
     def pattern(self, val):
         """Setter for pattern.
@@ -318,8 +324,8 @@ class CompletionFilterModel(QSortFilterProxyModel):
         """
         if parent == QModelIndex():
             return True
-        idx = self.sourceModel().index(row, 0, parent)
-        data = self.sourceModel().data(idx).value()
+        idx = self.srcmodel.index(row, 0, parent)
+        data = self.srcmodel.data(idx).value()
         # TODO more sophisticated filtering
         if not self.pattern:
             return True
@@ -334,8 +340,8 @@ class CompletionFilterModel(QSortFilterProxyModel):
         Prefers all items which start with self.pattern. Other than that, uses
         normal Python string sorting.
         """
-        left = self.sourceModel().data(lindex).value()
-        right = self.sourceModel().data(rindex).value()
+        left = self.srcmodel.data(lindex).value()
+        right = self.srcmodel.data(rindex).value()
 
         leftstart = left.startswith(self.pattern)
         rightstart = right.startswith(self.pattern)
diff --git a/qutebrowser/widgets/completion.py b/qutebrowser/widgets/completion.py
index 27f1a8f92..0453b145a 100644
--- a/qutebrowser/widgets/completion.py
+++ b/qutebrowser/widgets/completion.py
@@ -73,11 +73,10 @@ class CompletionView(QTreeView):
         self.completion_models['command'] = CommandCompletionModel()
         self.model = CompletionFilterModel()
         self.setModel(self.model)
-        self.model.setSourceModel(self.completion_models['command'])
+        self.setmodel('command')
         self.setItemDelegate(CompletionItemDelegate())
         self.setStyleSheet(config.get_stylesheet(self._stylesheet))
         self.setSizePolicy(QSizePolicy.Fixed, QSizePolicy.Minimum)
-        self.expandAll()
         self.setHeaderHidden(True)
         self.setIndentation(0)
         self.setItemsExpandable(False)
@@ -109,8 +108,7 @@ class CompletionView(QTreeView):
 
         model -- A QAbstractItemModel with available completions.
         """
-        self.model.setSourceModel(self.completion_models[model])
-        self.model.pattern = ''
+        self.model.setsrc(self.completion_models[model])
         self.expandAll()
 
     def resize_to_bar(self, geom):
@@ -147,7 +145,7 @@ class CompletionView(QTreeView):
         self.setmodel('command')
         text = text.lstrip(':')
         self.model.pattern = text
-        self.model.sourceModel().mark_all_items(text)
+        self.model.srcmodel.mark_all_items(text)
         if self.enabled:
             self.show()