diff --git a/changelog.d/14944.bugfix b/changelog.d/14944.bugfix
new file mode 100644
index 000000000..5fe1fb322
--- /dev/null
+++ b/changelog.d/14944.bugfix
@@ -0,0 +1 @@
+Fix a bug introduced in Synapse v1.64 where boolean power levels were erroneously permitted in [v10 rooms](https://spec.matrix.org/v1.5/rooms/v10/).
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index c4a7b1641..e0be9f88c 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -875,11 +875,11 @@ def _check_power_levels(
                 "kick",
                 "invite",
             }:
-                if not isinstance(v, int):
+                if type(v) is not int:
                     raise SynapseError(400, f"{v!r} must be an integer.")
             if k in {"events", "notifications", "users"}:
                 if not isinstance(v, collections.abc.Mapping) or not all(
-                    isinstance(v, int) for v in v.values()
+                    type(v) is int for v in v.values()
                 ):
                     raise SynapseError(
                         400,
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 52e4b467e..ebf8c7ed8 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -648,10 +648,10 @@ def _copy_power_level_value_as_integer(
 ) -> None:
     """Set `power_levels[key]` to the integer represented by `old_value`.
 
-    :raises TypeError: if `old_value` is not an integer, nor a base-10 string
+    :raises TypeError: if `old_value` is neither an integer nor a base-10 string
         representation of an integer.
     """
-    if isinstance(old_value, int):
+    if type(old_value) is int:
         power_levels[key] = old_value
         return
 
@@ -679,7 +679,7 @@ def validate_canonicaljson(value: Any) -> None:
     * Floats
     * NaN, Infinity, -Infinity
     """
-    if isinstance(value, int):
+    if type(value) is int:
         if value < CANONICALJSON_MIN_INT or CANONICALJSON_MAX_INT < value:
             raise SynapseError(400, "JSON integer out of range", Codes.BAD_JSON)
 
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 6bd474214..29fae716f 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -280,7 +280,7 @@ def event_from_pdu_json(pdu_json: JsonDict, room_version: RoomVersion) -> EventB
         _strip_unsigned_values(pdu_json)
 
     depth = pdu_json["depth"]
-    if not isinstance(depth, int):
+    if type(depth) is not int:
         raise SynapseError(400, "Depth %r not an intger" % (depth,), Codes.BAD_JSON)
 
     if depth < 0: