diff --git a/doc/changelog.asciidoc b/doc/changelog.asciidoc
index 07b11207a..1b97a906b 100644
--- a/doc/changelog.asciidoc
+++ b/doc/changelog.asciidoc
@@ -21,7 +21,8 @@ v1.4.0 (unreleased)
 Added
 ~~~~~
 
-- Support for the bundled `sip` module in PyQt 5.11.
+- Support for the bundled `sip` module in PyQt 5.11 and workarounds for
+  PyQt 5.11 bugs.
 - New `--debug-flag log-requests` to log requests to the debug log for
   debugging.
 - New `--first` flag for `:hint` (bound to `gi` for inputs) which automatically
diff --git a/qutebrowser/browser/downloads.py b/qutebrowser/browser/downloads.py
index 2e30c26c2..b06cedbfd 100644
--- a/qutebrowser/browser/downloads.py
+++ b/qutebrowser/browser/downloads.py
@@ -30,7 +30,7 @@ import tempfile
 import enum
 
 from PyQt5.QtCore import (pyqtSlot, pyqtSignal, Qt, QObject, QModelIndex,
-                          QTimer, QAbstractListModel, QUrl)
+                          QTimer, QAbstractListModel, QUrl, PYQT_VERSION)
 
 from qutebrowser.commands import cmdexc, cmdutils
 from qutebrowser.config import config
@@ -878,6 +878,11 @@ class DownloadModel(QAbstractListModel):
 
     """A list model showing downloads."""
 
+    if PYQT_VERSION == 0x050b00:
+        # WORKAROUND for PyQt 5.11 bug:
+        # https://www.riverbankcomputing.com/pipermail/pyqt/2018-June/040445.html
+        headerDataChanged = pyqtSignal(Qt.Orientation, int, int)
+
     def __init__(self, qtnetwork_manager, webengine_manager=None, parent=None):
         super().__init__(parent)
         self._qtnetwork_manager = qtnetwork_manager
diff --git a/qutebrowser/completion/models/completionmodel.py b/qutebrowser/completion/models/completionmodel.py
index 1c77e1d31..633d425d9 100644
--- a/qutebrowser/completion/models/completionmodel.py
+++ b/qutebrowser/completion/models/completionmodel.py
@@ -19,7 +19,8 @@
 
 """A model that proxies access to one or more completion categories."""
 
-from PyQt5.QtCore import Qt, QModelIndex, QAbstractItemModel
+from PyQt5.QtCore import (Qt, QModelIndex, QAbstractItemModel, pyqtSignal,
+                          PYQT_VERSION)
 
 from qutebrowser.utils import log, qtutils
 from qutebrowser.commands import cmdexc
@@ -38,6 +39,11 @@ class CompletionModel(QAbstractItemModel):
         _categories: The sub-categories.
     """
 
+    if PYQT_VERSION == 0x050b00:
+        # WORKAROUND for PyQt 5.11 bug:
+        # https://www.riverbankcomputing.com/pipermail/pyqt/2018-June/040445.html
+        headerDataChanged = pyqtSignal(Qt.Orientation, int, int)
+
     def __init__(self, *, column_widths=(30, 70, 0), parent=None):
         super().__init__(parent)
         self.column_widths = column_widths
diff --git a/qutebrowser/completion/models/histcategory.py b/qutebrowser/completion/models/histcategory.py
index 60f801492..06fa487ed 100644
--- a/qutebrowser/completion/models/histcategory.py
+++ b/qutebrowser/completion/models/histcategory.py
@@ -19,6 +19,7 @@
 
 """A completion category that queries the SQL History store."""
 
+from PyQt5.QtCore import pyqtSignal, Qt, PYQT_VERSION
 from PyQt5.QtSql import QSqlQueryModel
 
 from qutebrowser.misc import sql
@@ -30,6 +31,11 @@ class HistoryCategory(QSqlQueryModel):
 
     """A completion category that queries the SQL History store."""
 
+    if PYQT_VERSION == 0x050b00:
+        # WORKAROUND for PyQt 5.11 bug:
+        # https://www.riverbankcomputing.com/pipermail/pyqt/2018-June/040445.html
+        headerDataChanged = pyqtSignal(Qt.Orientation, int, int)
+
     def __init__(self, *, delete_func=None, parent=None):
         """Create a new History completion category."""
         super().__init__(parent=parent)
diff --git a/qutebrowser/completion/models/listcategory.py b/qutebrowser/completion/models/listcategory.py
index 13bc1e6b2..1d0c41e99 100644
--- a/qutebrowser/completion/models/listcategory.py
+++ b/qutebrowser/completion/models/listcategory.py
@@ -21,7 +21,8 @@
 
 import re
 
-from PyQt5.QtCore import Qt, QSortFilterProxyModel, QRegExp
+from PyQt5.QtCore import (Qt, QSortFilterProxyModel, QRegExp, PYQT_VERSION,
+                          pyqtSignal)
 from PyQt5.QtGui import QStandardItem, QStandardItemModel
 
 from qutebrowser.utils import qtutils
@@ -31,6 +32,11 @@ class ListCategory(QSortFilterProxyModel):
 
     """Expose a list of items as a category for the CompletionModel."""
 
+    if PYQT_VERSION == 0x050b00:
+        # WORKAROUND for PyQt 5.11 bug:
+        # https://www.riverbankcomputing.com/pipermail/pyqt/2018-June/040445.html
+        headerDataChanged = pyqtSignal(Qt.Orientation, int, int)
+
     def __init__(self, name, items, sort=True, delete_func=None, parent=None):
         super().__init__(parent)
         self.name = name