diff --git a/src/plugin_system/plugin_manager.py b/src/plugin_system/plugin_manager.py
index b72c4f02..2c8de821 100644
--- a/src/plugin_system/plugin_manager.py
+++ b/src/plugin_system/plugin_manager.py
@@ -8,6 +8,7 @@ API Version: 1.0.0
 """
 
 import json
+import math
 import queue
 import sys
 import time
@@ -793,6 +794,11 @@ class PluginManager:
             return None
         if requested is None:
             return None
+        if isinstance(requested, bool):
+            self.logger.debug(
+                "get_update_interval() returned a bool for %s, which is not a number",
+                plugin_id)
+            return None
         try:
             requested = float(requested)
         except (TypeError, ValueError):
@@ -800,7 +806,7 @@ class PluginManager:
                 "get_update_interval() returned %r for %s, which is not a number",
                 requested, plugin_id)
             return None
-        if requested != requested or requested == float('inf'):  # NaN / inf
+        if not math.isfinite(requested):  # NaN / +inf / -inf
             return None
         return max(requested, self.MIN_DYNAMIC_UPDATE_INTERVAL)
 
diff --git a/test/test_plugin_dynamic_update_interval.py b/test/test_plugin_dynamic_update_interval.py
index e87cf104..bd70fce0 100644
--- a/test/test_plugin_dynamic_update_interval.py
+++ b/test/test_plugin_dynamic_update_interval.py
@@ -98,10 +98,16 @@ class TestABrokenHookCannotStopUpdates:
     def test_a_non_numeric_hook_falls_back(self, manager, junk):
         assert manager._get_plugin_update_interval("sports", _Plugin(wants=junk)) == 60.0
 
-    @pytest.mark.parametrize("junk", [float("nan"), float("inf")])
+    @pytest.mark.parametrize("junk", [float("nan"), float("inf"), float("-inf")])
     def test_nan_and_infinity_fall_back(self, manager, junk):
         assert manager._get_plugin_update_interval("sports", _Plugin(wants=junk)) == 60.0
 
+    @pytest.mark.parametrize("junk", [True, False])
+    def test_a_bool_hook_falls_back(self, manager, junk):
+        """bool is a subclass of int, so it must be rejected before float()
+        turns it into 0.0/1.0 and the floor silently swallows the mistake."""
+        assert manager._get_plugin_update_interval("sports", _Plugin(wants=junk)) == 60.0
+
 
 class TestTheFloor:
     """A plugin asking for 0 would be re-entered on every tick of the render