diff --git a/pkgs/development/libraries/libwebsockets/default.nix b/pkgs/development/libraries/libwebsockets/default.nix
index 8f749d9fe6a..285a1628649 100644
--- a/pkgs/development/libraries/libwebsockets/default.nix
+++ b/pkgs/development/libraries/libwebsockets/default.nix
@@ -50,7 +50,7 @@ rec {
   };
 
   libwebsockets_4_0 = generic {
-    version = "4.0.1";
-    sha256 = "1pf7km0w5q7dqlwcwqizdpfqgg10prfq8g2c093f5nghwsfv8mmf";
+    version = "4.0.21";
+    sha256 = "01k05x4711ngin598jr9dag4ml3m7hi6pkgr4dsb02ryh1kc6146";
   };
 }