diff --git a/artiq-fast/conda/builder-env.nix b/artiq-fast/conda/builder-env.nix
index e1f3b8a..e6748a1 100644
--- a/artiq-fast/conda/builder-env.nix
+++ b/artiq-fast/conda/builder-env.nix
@@ -3,14 +3,21 @@
 with pkgs;
 
 let
-  condaDeps = [ stdenv.cc xorg.libSM xorg.libICE xorg.libX11 xorg.libXau xorg.libXi xorg.libXrender libselinux libGL ];
+  condaDeps = [ stdenv.cc zlib xorg.libSM xorg.libICE xorg.libX11 xorg.libXau xorg.libXi xorg.libXrender libselinux libGL ];
   # Use the full Anaconda distribution, which already contains conda-build and its many dependencies,
   # so we don't have to manually deal with them.
   condaInstaller = fetchurl {
-    url = "https://repo.anaconda.com/archive/Anaconda3-2019.03-Linux-x86_64.sh";
-    sha256 = "0fmpdd5876ylds98mydmv5klnwlzasa461k0l1f4vhbw96vm3j25";
+    url = "https://repo.anaconda.com/archive/Anaconda3-2021.05-Linux-x86_64.sh";
+    sha256 = "0lrxwd3pwz8k3jxwgkd9x47wgkqqy9s8m7hgx1x2gw4gcwysnl97";
   };
-  condaSrcChmod = runCommand "conda-src-chmod" { } "mkdir $out; cp ${condaInstaller} $out/conda-installer.sh; chmod +x $out/conda-installer.sh";
+  condaSrcChmod = runCommand "conda-src-chmod" { }
+    ''
+    mkdir $out
+    cp ${condaInstaller} $out/conda-installer.sh
+    chmod +x $out/conda-installer.sh
+    # keep the same file length to avoid breaking embedded payload offsets
+    sed -i 0,/unset\ LD_LIBRARY_PATH/s//\#nset\ LD_LIBRARY_PATH/ $out/conda-installer.sh
+    '';
   condaInstallerEnv = buildFHSUserEnv {
     name = "conda-installer-env";
     targetPkgs = pkgs: ([ condaSrcChmod ] ++ condaDeps);
@@ -26,7 +33,7 @@ let
   condaInstalled = runCommand "conda-installed" { }
     ''
     ${condaInstallerEnv}/bin/conda-installer-env -c "${condaSrcChmod}/conda-installer.sh -p $out -b"
-    substituteInPlace $out/lib/python3.7/site-packages/conda/gateways/disk/__init__.py \
+    substituteInPlace $out/lib/python3.8/site-packages/conda/gateways/disk/__init__.py \
       --replace "os.chmod(path, 0o2775)" "pass"
 
     # The conda garbage breaks if the package filename is prefixed with the Nix store hash.