diff --git a/CHANGES.rst b/CHANGES.rst
index 13ef88a..d0b7d04 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -23,6 +23,11 @@
   it properly lets the default Sphinx theme be used (by setting both
   ``default.css`` and ``layout.html`` to empty values).
 
+- Ignore bad eggs in the documentation working set. Previously they
+  would raise internal errors without any explanation. Now, they log a
+  warning pinpointing the bad egg. Fixes `issue 6
+  <https://github.com/zopefoundation/z3c.recipe.sphinxdoc/issues/6>`_.
+
 
 1.0.0 (2013-02-23)
 ==================
diff --git a/setup.py b/setup.py
index 24b4ec6..d8b23d5 100755
--- a/setup.py
+++ b/setup.py
@@ -70,6 +70,7 @@ def read(*rnames):
     ],
     extras_require={
         'test': [
+            'zope.testing',
             'zope.testrunner',
         ],
     },
diff --git a/src/z3c/recipe/sphinxdoc/__init__.py b/src/z3c/recipe/sphinxdoc/__init__.py
index 23d2245..4f3c5ac 100644
--- a/src/z3c/recipe/sphinxdoc/__init__.py
+++ b/src/z3c/recipe/sphinxdoc/__init__.py
@@ -12,6 +12,7 @@
 #
 ##############################################################################
 from __future__ import print_function
+
 import sys
 import os
 from os.path import join, dirname, isdir, normpath
@@ -28,6 +29,8 @@
     # Py3 location changed.
     from urllib.request import urlopen
 
+logger = __import__('logging').getLogger(__name__)
+
 confPyTemplate = """
 templates_path = ['%(templatesDir)s']
 source_suffix = '.rst'
@@ -91,7 +94,7 @@ def install(self):
         eggs, workingSet = self.egg.working_set()
         if 'doc-eggs' in self.options:
             eggs = self.options['doc-eggs'].split()
-        docs = [workingSet.find(pkg_resources.Requirement.parse(spec))
+        docs = [(workingSet.find(pkg_resources.Requirement.parse(spec)), spec)
                 for spec in eggs]
 
         # Create parts directory for configuration files.
@@ -105,8 +108,12 @@ def install(self):
         projectsData = {}
         # Preserve projectsData for testing
         self._projectsData = projectsData
-        #for each egg listed as a buildout option, create a configuration space.
-        for doc in docs:
+        # for each egg listed as a buildout option, create a configuration space.
+        for doc, egg_name in docs:
+            if not doc:
+                logger.warning("Specified egg '%s' cannot be resolved, ignoring.", egg_name)
+                continue
+
             partDir = join(installDir, doc.project_name)
             if not isdir(partDir):
                 os.mkdir(partDir)
diff --git a/src/z3c/recipe/sphinxdoc/tests/test_sphinxdoc.py b/src/z3c/recipe/sphinxdoc/tests/test_sphinxdoc.py
index 4580a2b..d744041 100644
--- a/src/z3c/recipe/sphinxdoc/tests/test_sphinxdoc.py
+++ b/src/z3c/recipe/sphinxdoc/tests/test_sphinxdoc.py
@@ -12,6 +12,7 @@
 #
 ##############################################################################
 
+import logging
 import shutil
 import subprocess
 import sys
@@ -38,10 +39,21 @@ def setUp(self):
         os.chdir(self.tmpdir)
         os.mkdir('bin')
 
+        # Sphinx likes to install handlers when you call its main methods.
+        # If we pass -W (and we do) those turn warnings into hard errors.
+        # This pollutes later tests. So be sure to tear those down.
+        self.handlers_before_set_up = logging.getLogger().handlers[:]
+
     def tearDown(self):
         os.chdir(self.here)
         shutil.rmtree(self.tmpdir)
 
+        root_logger = logging.getLogger()
+        for handler in root_logger.handlers[:]:
+            root_logger.removeHandler(handler)
+        for handler in self.handlers_before_set_up:
+            root_logger.addHandler(handler)
+
     def _makeOne(self, name='docs', options=None):
         opts = {
             'doc-eggs': 'z3c.recipe.sphinxdoc',
@@ -96,8 +108,8 @@ def test_openfile_falls_to_url(self):
         self.assertRaises(IOError,
                           docs.openfile, 'file:///')
 
-    def test_basic_install(self):
-        docs, _ = self._makeOne()
+    def test_basic_install(self, options=None):
+        docs, _ = self._makeOne(options=options)
         docs.install()
         self._check_conf_py_can_be_evald()
         conf = self._read_conf_file()
@@ -126,6 +138,22 @@ def test_basic_install(self):
 
         sphinxdoc.main(docs._projectsData, argv=['docs'], exit_on_error=True)
 
+    def test_install_with_bad_doc_egg(self):
+        from zope.testing.loggingsupport import InstalledHandler
+        handler = InstalledHandler('z3c.recipe.sphinxdoc')
+        self.addCleanup(handler.uninstall)
+
+        self.test_basic_install(options={
+            'doc-eggs': 'z3c.recipe.sphinxdoc this.egg.is.not.installed'
+        })
+
+        log_records = handler.records
+        self.assertEqual(1, len(log_records))
+        record = log_records[0]
+        self.assertEqual("WARNING", record.levelname)
+        self.assertEqual("Specified egg 'this.egg.is.not.installed' cannot be resolved, ignoring.",
+                         record.getMessage())
+
     def test_override_css(self):
         docs, _ = self._makeOne(options={'default.css': EMPTY_FILE})
         docs.install()