diff --git a/sphinxcontrib/confluencebuilder/config/defaults.py b/sphinxcontrib/confluencebuilder/config/defaults.py
index a3ac7d44..1b99ca73 100644
--- a/sphinxcontrib/confluencebuilder/config/defaults.py
+++ b/sphinxcontrib/confluencebuilder/config/defaults.py
@@ -91,16 +91,16 @@ def apply_defaults(builder):
 
     # ensure confluence_publish_debug is set with its expected enum value
     publish_debug = conf.confluence_publish_debug
-    if publish_debug is not None and publish_debug is not False:
+    if not isinstance(publish_debug, PublishDebug):
         # a boolean-provided publish debug is deprecated, but we will accept
         # it as its original implementation as an indication to enable
         # urllib3 logs
         if publish_debug is True:
             conf.confluence_publish_debug = PublishDebug.urllib3
-        elif not isinstance(publish_debug, PublishDebug):
+        elif isinstance(publish_debug, str) and publish_debug:
             conf.confluence_publish_debug = PublishDebug[publish_debug.lower()]
-    else:
-        conf.confluence_publish_debug = PublishDebug.none
+        else:
+            conf.confluence_publish_debug = PublishDebug.none
 
     if conf.confluence_publish_intersphinx is None:
         conf.confluence_publish_intersphinx = True
diff --git a/tests/unit-tests/test_config_checks.py b/tests/unit-tests/test_config_checks.py
index 2cb5d8fa..f052002a 100644
--- a/tests/unit-tests/test_config_checks.py
+++ b/tests/unit-tests/test_config_checks.py
@@ -630,6 +630,25 @@ def test_config_check_publish(self):
         with self.assertRaises(ConfluenceConfigError):
             self._try_config()
 
+    def test_config_check_publish_debug(self):
+        self.config['confluence_publish_debug'] = ''
+        self._try_config()
+
+        self.config['confluence_publish_debug'] = 'urllib3'
+        self._try_config()
+
+        self.config['confluence_publish_debug'] = 'unknown-entry'
+        with self.assertRaises(ConfluenceConfigError):
+            self._try_config()
+
+        self.config['confluence_publish_debug'] = [1, 2, 3]
+        with self.assertRaises(ConfluenceConfigError):
+            self._try_config()
+
+        self.config['confluence_publish_debug'] = True
+        with self.assertRaises(SphinxWarning):
+            self._try_config()
+
     def test_config_check_publish_delay(self):
         self.config['confluence_publish_delay'] = 0.3
         self._try_config()