diff --git a/pkgs/applications/science/math/gap/default.nix b/pkgs/applications/science/math/gap/default.nix
index 3d9e06527c9d..87071c0a7ae3 100644
--- a/pkgs/applications/science/math/gap/default.nix
+++ b/pkgs/applications/science/math/gap/default.nix
@@ -1,29 +1,80 @@
-{ stdenv, fetchurl, m4, gmp }:
-
-let
-  baseName = "gap";
-  version = "4r8p3";
-
-  pkgVer = "2016_03_19-22_17";
-in
+{ stdenv
+, fetchurl
+, fetchpatch
+, m4
+, gmp
+# don't remove any packages -- results in a ~1.3G size increase
+# see https://github.com/NixOS/nixpkgs/pull/38754 for a discussion
+, keepAllPackages ? true
+}:
 
 stdenv.mkDerivation rec {
-  name = "${baseName}-${version}";
+  pname = "gap";
+  # https://www.gap-system.org/Releases/
+  # newer versions (4.9.0) are available, but still considered beta (https://github.com/gap-system/gap/wiki/GAP-4.9-release-notes)
+  version = "4r8p10";
+  pkgVer = "2018_01_15-13_02";
+  name = "${pname}-${version}";
 
-  src = fetchurl {
-    url = "ftp://ftp.gap-system.org/pub/gap/gap48/tar.gz/${baseName}${version}_${pkgVer}.tar.gz";
-    sha256 = "1rmb0lj43avv456sjwb7ia3y0wwk5shlqylpkdwnnqpjnvjbnzv6";
+  src = let
+    # 4r8p10 -> 48
+    majorminor = stdenv.lib.replaceStrings ["r"] [""] (
+      builtins.head (stdenv.lib.splitString "p" version) # 4r8p10 -> 4r8
+    );
+  in
+    fetchurl {
+    url = "https://www.gap-system.org/pub/gap/gap${majorminor}/tar.bz2/gap${version}_${pkgVer}.tar.bz2";
+    sha256 = "0wzfdjnn6sfiaizbk5c7x44rhbfayis4lf57qbqqg84c7dqlwr6f";
   };
 
+  # remove all non-essential packages (which take up a lot of space)
+  preConfigure = stdenv.lib.optionalString (!keepAllPackages) ''
+    find pkg -type d -maxdepth 1 -mindepth 1 \
+       -not -name 'GAPDoc-*' \
+       -not -name 'autpgrp*' \
+       -exec echo "Removing package {}" \; \
+       -exec rm -r {} \;
+  '';
+
   configureFlags = [ "--with-gmp=system" ];
   buildInputs = [ m4 gmp ];
-  
+
+  patches = [
+    #  fix infinite loop in writeandcheck() when writing an error message fails.
+    (fetchpatch {
+      url = "https://git.sagemath.org/sage.git/plain/build/pkgs/gap/patches/writeandcheck.patch?id=07d6c37d18811e2b377a9689790a7c5e24da16ba";
+      sha256 = "1r1511x4kc2i2mbdq1b61rb6p3misvkf1v5qy3z6fmn6vqwziaz1";
+    })
+  ];
+
+  doCheck = true;
+  checkTarget = "testinstall";
+  # "teststandard" is a superset of testinstall. It takes ~1h instead of ~1min.
+  # tests are run twice, once with all packages loaded and once without
+  # checkTarget = "teststandard";
+
+  preCheck = ''
+    # gap tests check that the home directory exists
+    export HOME="$TMP/gap-home"
+    mkdir -p "$HOME"
+  '';
+
+  postCheck = ''
+    # The testsuite doesn't exit with a non-zero exit code on failure.
+    # It leaves its logs in dev/log however.
+
+    # grep for error messages
+    if grep ^##### dev/log/*; then
+        exit 1
+    fi
+  '';
+
   postBuild = ''
     pushd pkg
     bash ../bin/BuildPackages.sh
     popd
   '';
-  
+
   installPhase = ''
     mkdir -p "$out/bin" "$out/share/gap/"
 
@@ -31,7 +82,7 @@ stdenv.mkDerivation rec {
 
     sed -e "/GAP_DIR=/aGAP_DIR='$out/share/gap/build-dir/'" -i "$out/share/gap/build-dir/bin/gap.sh"
 
-    ln -s "$out/share/gap/build-dir/bin/gap.sh" "$out/bin"
+    ln -s "$out/share/gap/build-dir/bin/gap.sh" "$out/bin/gap"
   '';
 
   meta = with stdenv.lib; {
@@ -42,6 +93,10 @@ stdenv.mkDerivation rec {
       chrisjefferson
     ];
     platforms = platforms.all;
+    # keeping all packages increases the package size considerably, wchich
+    # is why a local build is preferable in that situation. The timeframe
+    # is reasonable and that way the binary cache doesn't get overloaded.
+    hydraPlatforms = stdenv.lib.optionals (!keepAllPackages) platforms;
     license = licenses.gpl2;
     homepage = http://gap-system.org/;
   };
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index c9bbbbf396c5..ee6bc16fb04b 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -20195,6 +20195,8 @@ with pkgs;
 
   gap = callPackage ../applications/science/math/gap { };
 
+  gap-minimal = lowPrio (gap.override { keepAllPackages = false; });
+
   geogebra = callPackage ../applications/science/math/geogebra { };
 
   maxima = callPackage ../applications/science/math/maxima {