diff --git a/pkgs/tools/networking/stunnel/default.nix b/pkgs/tools/networking/stunnel/default.nix
index e37aaf77f0d6..c87db08e88a9 100644
--- a/pkgs/tools/networking/stunnel/default.nix
+++ b/pkgs/tools/networking/stunnel/default.nix
@@ -1,24 +1,15 @@
-{ lib, stdenv, fetchurl, fetchpatch, openssl, nixosTests }:
+{ lib, stdenv, fetchurl, openssl, nixosTests }:
 
 stdenv.mkDerivation rec {
   pname = "stunnel";
-  version = "5.65";
+  version = "5.66";
 
   src = fetchurl {
     url    = "https://www.stunnel.org/downloads/${pname}-${version}.tar.gz";
-    sha256 = "60c500063bd1feff2877f5726e38278c086f96c178f03f09d264a2012d6bf7fc";
+    sha256 = "558178704d1aa5f6883aac6cc5d6bbf2a5714c8a0d2e91da0392468cee9f579c";
     # please use the contents of "https://www.stunnel.org/downloads/stunnel-${version}.tar.gz.sha256",
     # not the output of `nix-prefetch-url`
   };
-  patches = [
-    # Fixes compilation on darwin, patch is from
-    # https://github.com/mtrojnar/stunnel/pull/15.
-    (fetchpatch {
-        name = "stunnel_darwin_environ.patch";
-        url = "https://github.com/mtrojnar/stunnel/commit/d41932f6d55f639cc921007c2e180a55ef88bf00.patch";
-        sha256 = "sha256-d2K/BHE6GxvDCBIbttCHEVwH9SCu0jggNvhVHkC/qto=";
-      })
-  ];
 
   buildInputs = [ openssl ];
   configureFlags = [