diff --git a/pkgs/applications/misc/slic3r/prusa3d.nix b/pkgs/applications/misc/slic3r/prusa3d.nix
index cc9133257a0..2f5486a0f4b 100644
--- a/pkgs/applications/misc/slic3r/prusa3d.nix
+++ b/pkgs/applications/misc/slic3r/prusa3d.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchFromGitHub, makeWrapper, which, cmake, perl, perlPackages,
+{ stdenv, lib, fetchFromGitHub, makeWrapper, which, cmake, perl, perlPackages,
   boost, tbb, wxGTK30, pkgconfig, gtk3, fetchurl, gtk2, libGLU,
   glew, eigen, curl, gtest, nlopt, pcre, xorg }:
 let
@@ -98,6 +98,10 @@ stdenv.mkDerivation rec {
     # seems to be the easiest way.
     sed -i "s|\''${PERL_VENDORARCH}|$out/lib/slic3r-prusa3d|g" xs/CMakeLists.txt
     sed -i "s|\''${PERL_VENDORLIB}|$out/lib/slic3r-prusa3d|g" xs/CMakeLists.txt
+  '' + lib.optionalString (lib.versionOlder "2.5" nlopt.version) ''
+    # Since version 2.5.0 of nlopt we need to link to libnlopt, as libnlopt_cxx
+    # now seems to be integrated into the main lib.
+    sed -i 's|nlopt_cxx|nlopt|g' xs/src/libnest2d/cmake_modules/FindNLopt.cmake
   '';
 
   postInstall = ''
@@ -114,7 +118,7 @@ stdenv.mkDerivation rec {
   src = fetchFromGitHub {
     owner = "prusa3d";
     repo = "Slic3r";
-    sha256 = "0068wwsjwmnxql7653vy3labcyslzf17kr8xdr4lg2jplm022hvy";
+    sha256 = "0crjrll8cjpkllval6abrqzvzp8g3rnb4vmwi5vivw0jvdv3w5y7";
     rev = "version_${version}";
   };
 
diff --git a/pkgs/development/libraries/nlopt/default.nix b/pkgs/development/libraries/nlopt/default.nix
index 48b7acf2896..bbbc818db63 100644
--- a/pkgs/development/libraries/nlopt/default.nix
+++ b/pkgs/development/libraries/nlopt/default.nix
@@ -1,13 +1,8 @@
 { fetchurl, stdenv, octave ? null, cmake }:
 
-let
-
-  version = "2.5.0";
-
-in
-
-stdenv.mkDerivation {
+stdenv.mkDerivation rec {
   name = "nlopt-${version}";
+  version = "2.5.0";
 
   src = fetchurl {
     url = "https://github.com/stevengj/nlopt/archive/v${version}.tar.gz";