diff --git a/pkgs/development/libraries/opencascade/6.5.nix b/pkgs/development/libraries/opencascade/6.5.nix
deleted file mode 100644
index 252a6bb0ad16..000000000000
--- a/pkgs/development/libraries/opencascade/6.5.nix
+++ /dev/null
@@ -1,47 +0,0 @@
-{stdenv, fetchurl, mesa, tcl, tk, file, libXmu, automake, autoconf, libtool, qt4,
-ftgl, freetype}:
-
-stdenv.mkDerivation rec {
-  name = "opencascade-6.5.5";
-  src = fetchurl {
-    url = http://files.opencascade.com/OCCT/OCC_6.5.5_release/OpenCASCADE655.tgz;
-    sha256 = "1dnik00adfh6dxvn9kgf35yjda8chbi05f71i9119idmmrcapipm";
-  };
-
-  buildInputs = [ mesa tcl tk file libXmu automake autoconf libtool qt4 ftgl freetype ];
-
-  preUnpack = ''
-    sourceRoot=`pwd`/ros
-  '';
-
-  preConfigure = ''
-    sh ./build_configure
-  '';
-
-  # -fpermissive helps building opencascade, although gcc detects a flaw in the code
-  # and reports an error otherwise. Further versions may fix that.
-  NIX_CFLAGS_COMPILE = "-fpermissive"
-  # https://bugzilla.redhat.com/show_bug.cgi?id=902561
-    + " -DUSE_INTERP_RESULT"
-  # https://bugs.freedesktop.org/show_bug.cgi?id=83631
-    + " -DGLX_GLXEXT_LEGACY";
-
-  hardeningDisable = [ "format" ];
-
-  configureFlags = [ "--with-tcl=${tcl}/lib" "--with-tk=${tk}/lib" "--with-qt=${qt4}" "--with-ftgl=${ftgl}" "--with-freetype=${freetype.dev}" ];
-
-  postInstall = ''
-    mv $out/inc $out/include
-    mkdir -p $out/share/doc/${name}
-    cp -R ../doc $out/share/doc/${name}
-  '';
-
-  enableParallelBuilding = true;
-
-  meta = {
-    description = "Open CASCADE Technology, libraries for 3D modeling and numerical simulation";
-    homepage = http://www.opencascade.org/;
-    maintainers = with stdenv.lib.maintainers; [viric];
-    platforms = with stdenv.lib.platforms; linux;
-  };
-}
diff --git a/pkgs/development/libraries/opencascade/default.nix b/pkgs/development/libraries/opencascade/default.nix
index 51581bca382d..58f9019d6e03 100644
--- a/pkgs/development/libraries/opencascade/default.nix
+++ b/pkgs/development/libraries/opencascade/default.nix
@@ -1,39 +1,22 @@
-{stdenv, fetchurl, mesa, tcl, tk, file, libXmu, cmake, qt4, freetype}:
+{stdenv, fetchurl, mesa, tcl, tk, file, libXmu, cmake, libtool, qt4,
+ftgl, freetype}:
 
 stdenv.mkDerivation rec {
-  name = "opencascade-6.6.0";
+  name = "opencascade-oce-0.17.2";
   src = fetchurl {
-    url = http://files.opencascade.com/OCCT/OCC_6.6.0_release/OpenCASCADE660.tgz;
-    sha256 = "0q2xn915w9skv9sj74lxnyv9g3b0yi1j04majyzxk6sv4nra97z3";
+    url = https://github.com/tpaviot/oce/archive/OCE-0.17.2.tar.gz;
+    sha256 = "0vpmnb0k5y2f7lpmwx9pg9yfq24zjvnsak5alzacncfm1hv9b6cd";
   };
 
-  buildInputs = [ cmake mesa tcl tk file libXmu qt4 freetype ];
+  buildInputs = [ mesa tcl tk file libXmu libtool qt4 ftgl freetype cmake ];
 
-  sourceRoot = "ros/adm/cmake";
-
-  cmakeFlags = [
-    "-D3RDPARTY_TCL_DIR=${tcl}"
-    "-D3RDPARTY_FREETYPE_DIR=${freetype.dev}"
-
-    # Not used on Linux but must be defined during configuration.
-    "-D3RDPARTY_FREETYPE_DLL=${freetype.dev}"
-  ];
+  preConfigure = ''
+    cmakeFlags="$cmakeFlags -DOCE_INSTALL_PREFIX=$out"
+  '';
 
   # https://bugs.freedesktop.org/show_bug.cgi?id=83631
   NIX_CFLAGS_COMPILE = "-DGLX_GLXEXT_LEGACY";
 
-  hardeningDisable = [ "format" ];
-
-  preConfigure = ''
-    cmakeFlags="$cmakeFlags -DINSTALL_DIR=$out"
-  '';
-
-  postInstall = ''
-    mv $out/inc $out/include
-    mkdir -p $out/share/doc/${name}
-    cp -R ../../../doc $out/share/doc/${name}
-  '';
-
   enableParallelBuilding = true;
 
   meta = {
diff --git a/pkgs/development/libraries/opencascade/oce.nix b/pkgs/development/libraries/opencascade/oce.nix
deleted file mode 100644
index 58f9019d6e03..000000000000
--- a/pkgs/development/libraries/opencascade/oce.nix
+++ /dev/null
@@ -1,28 +0,0 @@
-{stdenv, fetchurl, mesa, tcl, tk, file, libXmu, cmake, libtool, qt4,
-ftgl, freetype}:
-
-stdenv.mkDerivation rec {
-  name = "opencascade-oce-0.17.2";
-  src = fetchurl {
-    url = https://github.com/tpaviot/oce/archive/OCE-0.17.2.tar.gz;
-    sha256 = "0vpmnb0k5y2f7lpmwx9pg9yfq24zjvnsak5alzacncfm1hv9b6cd";
-  };
-
-  buildInputs = [ mesa tcl tk file libXmu libtool qt4 ftgl freetype cmake ];
-
-  preConfigure = ''
-    cmakeFlags="$cmakeFlags -DOCE_INSTALL_PREFIX=$out"
-  '';
-
-  # https://bugs.freedesktop.org/show_bug.cgi?id=83631
-  NIX_CFLAGS_COMPILE = "-DGLX_GLXEXT_LEGACY";
-
-  enableParallelBuilding = true;
-
-  meta = {
-    description = "Open CASCADE Technology, libraries for 3D modeling and numerical simulation";
-    homepage = http://www.opencascade.org/;
-    maintainers = with stdenv.lib.maintainers; [viric];
-    platforms = with stdenv.lib.platforms; linux;
-  };
-}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 04d73ec807a1..a3ccba213176 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -9906,17 +9906,9 @@ with pkgs;
 
   openbabel = callPackage ../development/libraries/openbabel { };
 
-  opencascade = callPackage ../development/libraries/opencascade {
-    tcl = tcl-8_5;
-    tk = tk-8_5;
-  };
+  opencascade = callPackage ../development/libraries/opencascade { };
 
-  opencascade_6_5 = callPackage ../development/libraries/opencascade/6.5.nix {
-    automake = automake111x;
-    ftgl = ftgl212;
-  };
-
-  opencascade_oce = callPackage ../development/libraries/opencascade/oce.nix { };
+  opencascade_oce = opencascade;
 
   opencl-headers = callPackage ../development/libraries/opencl-headers { };
 
@@ -14546,7 +14538,6 @@ with pkgs;
 
   freecad = callPackage ../applications/graphics/freecad {
     boost = boost155;
-    opencascade = opencascade_oce;
   };
 
   freemind = callPackage ../applications/misc/freemind { };