diff --git a/pkgs/development/haskell-modules/configuration-nix.nix b/pkgs/development/haskell-modules/configuration-nix.nix
index f87aee89d453..d7f64e0ce04c 100644
--- a/pkgs/development/haskell-modules/configuration-nix.nix
+++ b/pkgs/development/haskell-modules/configuration-nix.nix
@@ -212,7 +212,19 @@ self: super: builtins.intersectAttrs super {
   mime-mail = appendConfigureFlag super.mime-mail "--ghc-option=-DMIME_MAIL_SENDMAIL_PATH=\"sendmail\"";
 
   # Help the test suite find system timezone data.
-  tz = overrideCabal super.tz (drv: { preConfigure = "export TZDIR=${pkgs.tzdata}/share/zoneinfo"; });
+  tz = overrideCabal super.tz (drv: {
+    preConfigure = "export TZDIR=${pkgs.tzdata}/share/zoneinfo";
+    patches = [
+      # Fix tests failing with libSystem, musl etc. due to a lack of
+      # support for glibc's non-POSIX TZDIR environment variable.
+      # https://github.com/nilcons/haskell-tz/pull/29
+      (pkgs.fetchpatch {
+        name = "support-non-glibc-tzset.patch";
+        url = "https://github.com/sternenseemann/haskell-tz/commit/64928f1a50a1a276a718491ae3eeef63abcdb393.patch";
+        sha256 = "1f53w8k1vpy39hzalyykpvm946ykkarj2714w988jdp4c2c4l4cf";
+      })
+    ] ++ (drv.patches or []);
+  });
 
   # Nix-specific workaround
   xmonad = appendPatch (dontCheck super.xmonad) ./patches/xmonad-nix.patch;