diff --git a/pkgs/applications/science/misc/root/setup-hook.sh b/pkgs/applications/science/misc/root/setup-hook.sh
index fc2b697d8a82..b26cf9b779f8 100644
--- a/pkgs/applications/science/misc/root/setup-hook.sh
+++ b/pkgs/applications/science/misc/root/setup-hook.sh
@@ -1,9 +1,13 @@
 thisroot () {
     # Workaround thisroot.sh dependency on man
-    if [ -z "${MANPATH}" ]; then
+    if [ -z "${MANPATH-}" ]; then
         MANPATH=:
     fi
+    local oldOpts="-u"
+    shopt -qo nounset || oldOpts="+u"
+    set +u
     source @out@/bin/thisroot.sh
+    set "$oldOpts"
 }
 
 postHooks+=(thisroot)
diff --git a/pkgs/development/libraries/physics/applgrid/default.nix b/pkgs/development/libraries/physics/applgrid/default.nix
index edda5148068a..3e2a53d81dd8 100644
--- a/pkgs/development/libraries/physics/applgrid/default.nix
+++ b/pkgs/development/libraries/physics/applgrid/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, gfortran, hoppet, lhapdf, root5 }:
+{ stdenv, fetchurl, gfortran, hoppet, lhapdf, root5, zlib }:
 
 stdenv.mkDerivation rec {
   pname = "applgrid";
@@ -9,7 +9,8 @@ stdenv.mkDerivation rec {
     sha256 = "1yw9wrk3vjv84kd3j4s1scfhinirknwk6xq0hvj7x2srx3h93q9p";
   };
 
-  buildInputs = [ gfortran hoppet lhapdf root5 ];
+  # For some reason zlib was only needed after bump to gfortran8
+  buildInputs = [ gfortran hoppet lhapdf root5 zlib ];
 
   patches = [
     ./bad_code.patch