diff --git a/src/calibre/ebooks/render_html.py b/src/calibre/ebooks/render_html.py
index 6d745a0eb1..ad367c6088 100644
--- a/src/calibre/ebooks/render_html.py
+++ b/src/calibre/ebooks/render_html.py
@@ -7,12 +7,18 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 import os
 import sys
 
-from PyQt5.Qt import QApplication, QMarginsF, QPageLayout, QPageSize, Qt, QUrl
+from PyQt5.Qt import (
+    QApplication, QMarginsF, QPageLayout, QPageSize, Qt, QTimer, QUrl
+)
 from PyQt5.QtWebEngineWidgets import QWebEnginePage
 
 from calibre.ebooks.metadata.pdf import page_images
 from calibre.gui2 import must_use_qt
 from calibre.gui2.webengine import secure_webengine
+from calibre.utils.monotonic import monotonic
+
+LOAD_TIMEOUT = 20
+PRINT_TIMEOUT = 10
 
 
 class Render(QWebEnginePage):
@@ -20,8 +26,12 @@ class Render(QWebEnginePage):
     def __init__(self):
         QWebEnginePage.__init__(self)
         secure_webengine(self)
+        self.printing_started = False
         self.loadFinished.connect(self.load_finished, type=Qt.QueuedConnection)
         self.pdfPrintingFinished.connect(self.print_finished)
+        self.hang_timer = t = QTimer(self)
+        t.setInterval(500)
+        t.timeout.connect(self.hang_check)
 
     def load_finished(self, ok):
         if ok:
@@ -29,13 +39,29 @@ class Render(QWebEnginePage):
         else:
             QApplication.instance().exit(1)
 
+    def start_load(self, path_to_html):
+        self.load(QUrl.fromLocalFile(path_to_html))
+        self.start_time = monotonic()
+        self.hang_timer.start()
+
+    def hang_check(self):
+        if self.printing_started:
+            if monotonic() - self.start_time > PRINT_TIMEOUT:
+                QApplication.instance().exit(4)
+        else:
+            if monotonic() - self.start_time > LOAD_TIMEOUT:
+                QApplication.instance().exit(3)
+
     def start_print(self):
         margins = QMarginsF(0, 0, 0, 0)
         page_layout = QPageLayout(QPageSize(QPageSize.A4), QPageLayout.Portrait, margins)
         self.printToPdf('rendered.pdf', page_layout)
+        self.printing_started = True
+        self.start_time = monotonic()
 
     def print_finished(self, path, ok):
         QApplication.instance().exit(0 if ok else 2)
+        self.hang_timer.stop()
 
 
 def main(path_to_html, tdir, image_format='jpeg'):
@@ -45,7 +71,7 @@ def main(path_to_html, tdir, image_format='jpeg'):
     path_to_html = os.path.abspath(path_to_html)
     os.chdir(tdir)
     renderer = Render()
-    renderer.load(QUrl.fromLocalFile(path_to_html))
+    renderer.start_load(path_to_html)
     ret = QApplication.instance().exec_()
     if ret == 0:
         page_images('rendered.pdf', image_format=image_format)
@@ -55,4 +81,5 @@ def main(path_to_html, tdir, image_format='jpeg'):
 
 
 if __name__ == '__main__':
-    main(sys.argv[-1], '.')
+    if not main(sys.argv[-1], '.'):
+        raise SystemExit('Failed to render HTML')