diff --git a/pkgs/tools/networking/mailsend/default.nix b/pkgs/tools/networking/mailsend/default.nix
index 13a6dc005dd8..ab1717da651a 100644
--- a/pkgs/tools/networking/mailsend/default.nix
+++ b/pkgs/tools/networking/mailsend/default.nix
@@ -1,4 +1,9 @@
-{ lib, stdenv, fetchurl, openssl }:
+{ lib
+, stdenv
+, fetchurl
+, fetchpatch
+, openssl
+}:
 
 stdenv.mkDerivation rec {
   pname = "mailsend";
@@ -21,7 +26,17 @@ stdenv.mkDerivation rec {
       url = "https://github.com/muquit/mailsend/commit/960df6d7a11eef90128dc2ae660866b27f0e4336.patch";
       sha256 = "0vz373zcfl19inflybfjwshcq06rvhx0i5g0f4b021cxfhyb1sm0";
     })
+    # Pull fix pending upstream inclusion for parallel build failures:
+    #   https://github.com/muquit/mailsend/pull/165
+    (fetchpatch {
+      name = "parallel-install.patch";
+      url = "https://github.com/muquit/mailsend/commit/acd4ebedbce0e4af3c7b6632f905f73e642ca38c.patch";
+      hash = "sha256-p8tNnkU6cMopuP63kVtRbD9aenhzL1EAXlvvFh4fucE=";
+    })
   ];
+
+  enableParallelBuilding = true;
+
   meta = with lib; {
     description = "CLI email sending tool";
     license = licenses.bsd3;