diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c324acd5..b89c019bf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - API Docs moved to https://js.waku.org/
 - test: fix typing for nwaku JSON RPC responses.
 
+### Fixed
+
+- Downgrade to @libp2p/mplex@5.1.2 to fix "Muxer already closed" issue.
+
 ## [0.26.0] - 2022-09-08
 
 ### Added
diff --git a/package-lock.json b/package-lock.json
index 4a99a45e9..aa54916ad 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -20,7 +20,7 @@
         "@libp2p/interface-peer-store": "^1.0.0",
         "@libp2p/interface-pubsub": "^2.0.1",
         "@libp2p/interfaces": "^3.0.2",
-        "@libp2p/mplex": "^5.1.1",
+        "@libp2p/mplex": "~5.1.2",
         "@libp2p/peer-id": "^1.1.10",
         "@libp2p/websockets": "^3.0.3",
         "@multiformats/multiaddr": "^10.4.0",
@@ -1239,9 +1239,9 @@
       }
     },
     "node_modules/@libp2p/mplex": {
-      "version": "5.1.1",
-      "resolved": "https://registry.npmjs.org/@libp2p/mplex/-/mplex-5.1.1.tgz",
-      "integrity": "sha512-a4hUUzHaFUmk6hx0lV6dveyOmHlOqB/MwDJJfIDyHvDILb2ZXGLJaI3JnbMYqPCwOCeSFkKu8Ixw5HphffV0Aw==",
+      "version": "5.1.2",
+      "resolved": "https://registry.npmjs.org/@libp2p/mplex/-/mplex-5.1.2.tgz",
+      "integrity": "sha512-PJcHwhUTXxtyG3lLjX9itBSPYuhReLn63KhJU8HsvFxi6KZC52mdOyDUuwMQr68QKcdZGP1K5sg5mRoC0U3PAw==",
       "dependencies": {
         "@libp2p/components": "^2.0.0",
         "@libp2p/interface-connection": "^3.0.1",
@@ -13102,9 +13102,9 @@
       }
     },
     "@libp2p/mplex": {
-      "version": "5.1.1",
-      "resolved": "https://registry.npmjs.org/@libp2p/mplex/-/mplex-5.1.1.tgz",
-      "integrity": "sha512-a4hUUzHaFUmk6hx0lV6dveyOmHlOqB/MwDJJfIDyHvDILb2ZXGLJaI3JnbMYqPCwOCeSFkKu8Ixw5HphffV0Aw==",
+      "version": "5.1.2",
+      "resolved": "https://registry.npmjs.org/@libp2p/mplex/-/mplex-5.1.2.tgz",
+      "integrity": "sha512-PJcHwhUTXxtyG3lLjX9itBSPYuhReLn63KhJU8HsvFxi6KZC52mdOyDUuwMQr68QKcdZGP1K5sg5mRoC0U3PAw==",
       "requires": {
         "@libp2p/components": "^2.0.0",
         "@libp2p/interface-connection": "^3.0.1",
diff --git a/package.json b/package.json
index 34c8e3c03..6cbbe4b62 100644
--- a/package.json
+++ b/package.json
@@ -100,7 +100,7 @@
     "@libp2p/interface-peer-store": "^1.0.0",
     "@libp2p/interface-pubsub": "^2.0.1",
     "@libp2p/interfaces": "^3.0.2",
-    "@libp2p/mplex": "^5.1.1",
+    "@libp2p/mplex": "~5.1.2",
     "@libp2p/peer-id": "^1.1.10",
     "@libp2p/websockets": "^3.0.3",
     "@multiformats/multiaddr": "^10.4.0",