diff --git a/package.json b/package.json
index 90314904c..e281939ae 100644
--- a/package.json
+++ b/package.json
@@ -58,7 +58,7 @@
     "i18next-http-backend": "^2.0.0",
     "livekit-client": "^1.12.3",
     "lodash": "^4.17.21",
-    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#6385c9c0dab8fe67bd3a8992a4777f243fdd1b68",
+    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#c8f8fb587d29dce22d314bfc16bf25a76b04e8bb",
     "matrix-widget-api": "^1.3.1",
     "normalize.css": "^8.0.1",
     "pako": "^2.0.4",
diff --git a/src/room/GroupCallView.tsx b/src/room/GroupCallView.tsx
index d238176e7..f834814e4 100644
--- a/src/room/GroupCallView.tsx
+++ b/src/room/GroupCallView.tsx
@@ -110,7 +110,7 @@ export function GroupCallView({
 
   // Count each member only once, regardless of how many devices they use
   const participantCount = useMemo(
-    () => new Set<string>(memberships.map((m) => m.member.userId)).size,
+    () => new Set<string>(memberships.map((m) => m.sender!)).size,
     [memberships]
   );
 
diff --git a/yarn.lock b/yarn.lock
index 57dfaf92f..cdc66da4e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7286,9 +7286,9 @@ matrix-events-sdk@0.0.1:
   resolved "https://registry.yarnpkg.com/matrix-events-sdk/-/matrix-events-sdk-0.0.1.tgz#c8c38911e2cb29023b0bbac8d6f32e0de2c957dd"
   integrity sha512-1QEOsXO+bhyCroIe2/A5OwaxHvBm7EsSQ46DEDn8RBIfQwN5HWBpFvyWWR4QY0KHPPnnJdI99wgRiAl7Ad5qaA==
 
-"matrix-js-sdk@github:matrix-org/matrix-js-sdk#6385c9c0dab8fe67bd3a8992a4777f243fdd1b68":
-  version "28.1.0"
-  resolved "https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/6385c9c0dab8fe67bd3a8992a4777f243fdd1b68"
+"matrix-js-sdk@github:matrix-org/matrix-js-sdk#c8f8fb587d29dce22d314bfc16bf25a76b04e8bb":
+  version "29.0.0"
+  resolved "https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/c8f8fb587d29dce22d314bfc16bf25a76b04e8bb"
   dependencies:
     "@babel/runtime" "^7.12.5"
     "@matrix-org/matrix-sdk-crypto-wasm" "^1.2.3-alpha.0"