diff --git a/pkgs/tools/archivers/innoextract/default.nix b/pkgs/tools/archivers/innoextract/default.nix
index 0f6814d53c99..546e9a7aad98 100644
--- a/pkgs/tools/archivers/innoextract/default.nix
+++ b/pkgs/tools/archivers/innoextract/default.nix
@@ -1,4 +1,6 @@
-{stdenv, fetchurl, cmake, python, doxygen, lzma, boost}:
+{ stdenv, fetchurl, cmake, doxygen, makeWrapper, python
+, boost, lzma
+, withGog ? false, unar ? null }:
 
 stdenv.mkDerivation rec {
   name = "innoextract-1.6";
@@ -8,14 +10,23 @@ stdenv.mkDerivation rec {
     sha256 = "0gh3q643l8qlwla030cmf3qdcdr85ixjygkb7j4dbm7zbwa3yik6";
   };
 
-  buildInputs = [ python doxygen lzma boost ];
-  nativeBuildInputs = [ cmake ];
+  buildInputs = [ python lzma boost ];
+
+  nativeBuildInputs = [ cmake makeWrapper ];
+
+  enableParallelBuilding = true;
+
+  # we need unar to for multi-archive extraction
+  postFixup = stdenv.lib.optionalString withGog ''
+    wrapProgram $out/bin/innoextract \
+      --prefix PATH : ${stdenv.lib.makeBinPath [ unar ]}
+  '';
 
   meta = with stdenv.lib; {
     description = "A tool to unpack installers created by Inno Setup";
     homepage = http://constexpr.org/innoextract/;
-    platforms = platforms.linux;
     license = licenses.zlib;
     maintainers = with maintainers; [ abbradar ];
+    platforms = platforms.linux;
   };
 }
diff --git a/pkgs/tools/archivers/unar/default.nix b/pkgs/tools/archivers/unar/default.nix
index 520742a1b3c7..1104548f77f8 100644
--- a/pkgs/tools/archivers/unar/default.nix
+++ b/pkgs/tools/archivers/unar/default.nix
@@ -1,8 +1,10 @@
 { stdenv, fetchurl, gnustep, unzip, bzip2, zlib, icu, openssl }:
 
-stdenv.mkDerivation rec {
-  name = "${pname}-${version}";
+let
   pname = "unar";
+
+in stdenv.mkDerivation rec {
+  name = "${pname}-${version}";
   version = "1.10.1";
 
   src = fetchurl {
@@ -10,23 +12,20 @@ stdenv.mkDerivation rec {
     sha256 = "0aq9zlar5vzr5qxphws8dm7ax60bsfsw77f4ciwa5dq5lla715j0";
   };
 
-  buildInputs = [
-    gnustep.make unzip gnustep.base bzip2.dev
-    zlib.dev icu.dev openssl.dev
-  ];
+  buildInputs = [ gnustep.base bzip2 icu openssl zlib ];
+
+  nativeBuildInputs = [ gnustep.make unzip ];
+
+  enableParallelBuilding = true;
 
   postPatch = ''
-    substituteInPlace Makefile.linux \
-      --replace "CC = gcc" "CC=cc" \
-      --replace "CXX = g++" "CXX=c++" \
-      --replace "OBJCC = gcc" "OBJCC=cc" \
-      --replace "OBJCXX = g++" "OBJCXX=c++"
-
-    substituteInPlace ../UniversalDetector/Makefile.linux \
-      --replace "CC = gcc" "CC=cc" \
-      --replace "CXX = g++" "CXX=c++" \
-      --replace "OBJCC = gcc" "OBJCC=c" \
-      --replace "OBJCXX = g++" "OBJCXX=c++"
+    for f in Makefile.linux ../UniversalDetector/Makefile.linux ; do
+      substituteInPlace $f \
+        --replace "CC = gcc"     "CC=cc" \
+        --replace "CXX = g++"    "CXX=c++" \
+        --replace "OBJCC = gcc"  "OBJCC=cc" \
+        --replace "OBJCXX = g++" "OBJCXX=c++"
+    done
   '';
 
   makefile = "Makefile.linux";
@@ -34,17 +33,16 @@ stdenv.mkDerivation rec {
   sourceRoot = "./The Unarchiver/XADMaster";
 
   installPhase = ''
-    mkdir -p $out/bin
-    cp lsar $out/bin
-    cp unar $out/bin
+    runHook preInstall
 
-    mkdir -p $out/share/man/man1
-    cp ../Extra/lsar.1 $out/share/man/man1
-    cp ../Extra/unar.1 $out/share/man/man1
+    install -Dm755 -t $out/bin lsar unar
+    install -Dm644 -t $out/share/man/man1 ../Extra/{lsar,unar}.1
 
     mkdir -p $out/etc/bash_completion.d
     cp ../Extra/lsar.bash_completion $out/etc/bash_completion.d/lsar
     cp ../Extra/unar.bash_completion $out/etc/bash_completion.d/unar
+
+    runHook postInstall
   '';
 
   meta = with stdenv.lib; {
@@ -55,7 +53,7 @@ stdenv.mkDerivation rec {
       zip, RAR, 7z, tar, gzip, bzip2, LZMA, XZ, CAB, MSI, NSIS, EXE, ISO, BIN, \
       and split file formats, as well as the old Stuffit, Stuffit X, DiskDouble, \
       Compact Pro, Packit, cpio, compress (.Z), ARJ, ARC, PAK, ACE, ZOO, LZH, \
-      ADF, DMS, LZX, PowerPacker, LBR, Squeeze, Crunch, and other old formats. 
+      ADF, DMS, LZX, PowerPacker, LBR, Squeeze, Crunch, and other old formats.
     '';
     license = with licenses; [ lgpl21Plus ];
     platforms = with platforms; linux;