diff --git a/pkgs/development/python-modules/magic-wormhole/default.nix b/pkgs/development/python-modules/magic-wormhole/default.nix
index 83152390624b..810a97f6e641 100644
--- a/pkgs/development/python-modules/magic-wormhole/default.nix
+++ b/pkgs/development/python-modules/magic-wormhole/default.nix
@@ -3,6 +3,7 @@
   stdenv,
   buildPythonPackage,
   fetchFromGitHub,
+  fetchpatch,
   installShellFiles,
 
   # build-system
@@ -41,16 +42,25 @@
 
 buildPythonPackage rec {
   pname = "magic-wormhole";
-  version = "0.19.2";
+  version = "0.20.0";
   pyproject = true;
 
   src = fetchFromGitHub {
     owner = "magic-wormhole";
     repo = "magic-wormhole";
     tag = version;
-    hash = "sha256-5Tipcood5RktXY05p20hQpWhSMMnZm67I4iybjV8TcA=";
+    hash = "sha256-YjzdznZZ/0YTU83f3jlOr6+yOWQ++R1wU9IZDrfAMpo=";
   };
 
+  patches = [
+    # TODO: drop when updating beyond version 0.20.0
+    (fetchpatch {
+      name = "SubchannelDemultiplex._pending_opens-fix-type.patch";
+      url = "https://github.com/magic-wormhole/magic-wormhole/commit/6d7f48786b5506df5b6a254bc4e37f6bf5d75593.patch";
+      hash = "sha256-28YH3enyQ9rTT56OU7FfFonb9l8beJ9QRgPoItzrgu4=";
+    })
+  ];
+
   postPatch =
     # enable tests by fixing the location of the wormhole binary
     ''
@@ -104,16 +114,17 @@ buildPythonPackage rec {
   ++ optional-dependencies.dilation
   ++ lib.optionals stdenv.hostPlatform.isDarwin [ unixtools.locale ];
 
-  enabledTestPaths = [ "src/wormhole/test" ];
-
   __darwinAllowLocalNetworking = true;
 
   postInstall = ''
     install -Dm644 docs/wormhole.1 $out/share/man/man1/wormhole.1
+
+    # https://github.com/magic-wormhole/magic-wormhole/issues/619
     installShellCompletion --cmd ${meta.mainProgram} \
       --bash wormhole_complete.bash \
       --fish wormhole_complete.fish \
       --zsh wormhole_complete.zsh
+    rm $out/wormhole_complete.*
   '';
 
   passthru.updateScript = gitUpdater { };