diff --git a/pkgs/by-name/sm/smux/package.nix b/pkgs/by-name/sm/smux/package.nix
index 4bc93de97d24..96532da7251b 100644
--- a/pkgs/by-name/sm/smux/package.nix
+++ b/pkgs/by-name/sm/smux/package.nix
@@ -12,16 +12,16 @@
 
 rustPlatform.buildRustPackage (finalAttrs: {
   pname = "smux";
-  version = "0.3.1";
+  version = "0.4.0";
 
   src = fetchFromGitHub {
     owner = "Aietes";
     repo = "smux";
     tag = "v${finalAttrs.version}";
-    hash = "sha256-mc7sspGN4Wf8Jn995S/jsZ0v1s5kgJ0ASn9iGbzH13U=";
+    hash = "sha256-oEnlxIRk41hqkoIqcJAIqm5VcGvXJ29M1pfz2tj+S48=";
   };
 
-  cargoHash = "sha256-nUJwIOdVmZR+inDz4kYpPTFXREyZyf891ATed6UFIJo=";
+  cargoHash = "sha256-P4uzdP4eOlL6TDOSzVf8s6U9DyO0HbAdGIcObDC06fU=";
 
   __structuredAttrs = true;
   strictDeps = true;