diff --git a/pkgs/applications/science/math/giac/default.nix b/pkgs/applications/science/math/giac/default.nix
index 6acaa4067440..dd92e264889f 100644
--- a/pkgs/applications/science/math/giac/default.nix
+++ b/pkgs/applications/science/math/giac/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, texlive, bison, flex
+{ stdenv, fetchurl, fetchpatch, texlive, bison, flex
 , gmp, mpfr, pari, ntl, gsl, blas, mpfi, liblapackWithAtlas
 , readline, gettext, libpng, libao, gfortran, perl
 , enableGUI ? false, libGLU_combined ? null, xorg ? null, fltk ? null
@@ -16,6 +16,15 @@ stdenv.mkDerivation rec {
     sha256 = "0dv5p5y6gkrsmz3xa7fw87rjyabwdwk09mqb09kb7gai9n9dgayk";
   };
 
+  patches = stdenv.lib.optionals (!enableGUI) [
+    # when enableGui is false, giac is compiled without fltk. That means some
+    # outputs differ in the make check. Patch around this:
+    (fetchpatch {
+      url    = "https://git.sagemath.org/sage.git/plain/build/pkgs/giac/patches/nofltk-check.patch?id=7553a3c8dfa7bcec07241a07e6a4e7dcf5bb4f26";
+      sha256 = "0xkmfc028vg5w6va04gp2x2iv31n8v4shd6vbyvk4blzgfmpj2cw";
+    })
+  ];
+
   postPatch = ''
     for i in doc/*/Makefile*; do
       substituteInPlace "$i" --replace "/bin/cp" "cp";
@@ -37,10 +46,11 @@ stdenv.mkDerivation rec {
     libGLU_combined fltk xorg.libX11
   ];
 
-  outputs = [ "out" ];
+  outputs = [ "out" "doc" ];
+
+  doCheck = true;
 
   enableParallelBuilding = true;
-  hardeningDisable = [ "format" "bindnow" "relro" ];
 
   configureFlags = [
     "--enable-gc" "--enable-png" "--enable-gsl" "--enable-lapack"
@@ -57,6 +67,13 @@ stdenv.mkDerivation rec {
     for file in $(find $out -name Makefile) ; do
       sed -i "s@/nix/store/[^/]*/bin/@@" "$file" ;
     done;
+
+    # reference cycle
+    rm "$out/share/giac/doc/el/"{casinter,tutoriel}/Makefile
+
+    mkdir -p "$doc/share/giac"
+    mv "$out/share/giac/doc" "$doc/share/giac"
+    mv "$out/share/giac/examples" "$doc/share/giac"
   '';
 
   meta = with stdenv.lib; {