diff --git a/openscad.pro b/openscad.pro
index 591ed5f3..048fbb54 100644
--- a/openscad.pro
+++ b/openscad.pro
@@ -108,6 +108,11 @@ CONFIG(mingw-cross-env) {
   include(mingw-cross-env.pri)
 }
 
+CONFIG(skip-version-check) {
+  # force the use of outdated libraries
+  DEFINES += OPENSCAD_SKIP_VERSION_CHECK
+}
+
 # Application configuration
 macx:CONFIG += mdi
 CONFIG += cgal
@@ -122,14 +127,7 @@ mdi {
   DEFINES += ENABLE_MDI
 }
 
-# FIXME: This can be made default by now
-CONFIG += progresswidget
-progresswidget {
-  DEFINES += USE_PROGRESSWIDGET
-  FORMS   += src/ProgressWidget.ui
-  HEADERS += src/ProgressWidget.h
-  SOURCES += src/ProgressWidget.cc
-}
+DEFINES += USE_PROGRESSWIDGET
 
 include(common.pri)
 
@@ -145,9 +143,12 @@ RESOURCES = openscad.qrc
 
 FORMS   += src/MainWindow.ui \
            src/Preferences.ui \
-           src/OpenCSGWarningDialog.ui
+           src/OpenCSGWarningDialog.ui \
+           src/ProgressWidget.ui
 
-HEADERS += src/parsersettings.h \
+HEADERS += src/version_check.h \
+           src/ProgressWidget.h \
+           src/parsersettings.h \
            src/renderer.h \
            src/rendersettings.h \
            src/ThrownTogetherRenderer.h \
@@ -203,8 +204,10 @@ HEADERS += src/parsersettings.h \
            src/system-gl.h \
            src/stl-utils.h
 
-SOURCES += src/mathc99.cc \
-	   src/linalg.cc \
+SOURCES += src/version_check.cc \
+           src/ProgressWidget.cc \
+           src/mathc99.cc \
+           src/linalg.cc \
            src/handle_dep.cc \
            src/value.cc \
            src/expr.cc \
diff --git a/src/cgal.h b/src/cgal.h
index 9810340f..e5e39dd0 100644
--- a/src/cgal.h
+++ b/src/cgal.h
@@ -11,11 +11,6 @@ using boost::intmax_t;
 using boost::uintmax_t;
 #endif
 
-#include <CGAL/version.h>
-#if CGAL_VERSION_NR < 1030601000
-  #error CGAL >= 3.6 is required!
-#endif
-
 // NDEBUG must be disabled when including CGAL headers, otherwise CGAL assertions
 // will not be thrown, causing OpenSCAD's CGAL error checking to fail.
 // To be on the safe side, this has to be done when including any CGAL header file.
diff --git a/src/version_check.cc b/src/version_check.cc
new file mode 100644
index 00000000..87dfeebd
--- /dev/null
+++ b/src/version_check.cc
@@ -0,0 +1,2 @@
+#include "version_check.h"
+
diff --git a/src/version_check.h b/src/version_check.h
new file mode 100644
index 00000000..45e00eca
--- /dev/null
+++ b/src/version_check.h
@@ -0,0 +1,107 @@
+// version_check.h copyright 2012 don bright. released under the GPL 2, or
+// later, as described in the file named 'COPYING' in OpenSCAD's project root.
+
+/* This file will check versions of libraries at compile time. If they
+are too old, the user will be warned. If the user wishes to force
+compilation, they can run
+
+ qmake CONFIG=skip-version-check
+
+Otherwise they will be guided to README.md and an -build-dependencies script.
+
+The extensive #else #endif is to ensure only a single error is printed at
+a time, to avoid confusion.
+*/
+
+#ifndef OPENSCAD_SKIP_VERSION_CHECK
+
+
+#include <gmp.h>
+// set minimum numbers here.
+#define GMPMAJOR 5
+#define GMPMINOR 0
+#define GMPPATCH 0
+#define SYS_GMP_VER  (__GNU_MP_VERSION * 10000 + __GNU_MP_VERSION_MINOR * 100 + __GNU_MP_VERSION_PATCHLEVEL * 1)
+#if SYS_GMP_VER < GMPMAJOR * 10000 + GMPMINOR * 100 + GMPPATCH * 1
+#error GNU GMP library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#else
+
+
+#include <mpfr.h>
+#if MPFR_VERSION < MPFR_VERSION_NUM( 3,0,0 )
+#error GNU MPFR library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#else
+
+
+#include <Eigen/Core>
+#if not EIGEN_VERSION_AT_LEAST( 2,0,13 )
+#error eigen2 library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#else
+
+
+#include <boost/version.hpp>
+// boost 1.3.5 = 103500
+#if BOOST_VERSION < 103500
+#error boost library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#else
+
+
+#ifdef ENABLE_CGAL
+#include <CGAL/version.h>
+
+#if CGAL_VERSION_NR < 1030601000
+#error CGAL library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#else
+
+#if CGAL_VERSION_NR < 1040001000
+#warning "======================="
+#warning "."
+#warning "."
+#warning "."
+#warning "."
+#warning CGAL library version is old, risking buggy behavior. Please see README.md. Compiling anyway.
+#warning "."
+#warning "."
+#warning "."
+#warning "."
+#warning "======================="
+#endif // CGAL_VERSION_NR < 10400010000
+#endif //ENABLE_CGAL
+
+#ifdef ENABLE_OPENCSG
+#include <GL/glew.h>
+// kludge - GLEW doesnt have compiler-accessible version numbering
+#ifndef GLEW_ARB_occlusion_query2
+#error GLEW library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#else
+
+
+#include <opencsg.h>
+// 1.3.2 -> 0x0132
+#if OPENCSG_VERSION < 0x0132
+#error OPENCSG library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#else
+#endif // ENABLE_OPENCSG
+
+#include <QtCore/qglobal.h>
+#if QT_VERSION < 0x040603
+#error QT library missing or version too old. See README.md. To force compile, run qmake CONFIG=skip-version-check
+#endif // QT
+
+
+#ifdef ENABLE_OPENCSG
+#endif // OpenCSG
+#endif // GLEW
+#endif // ENABLE_OPENCSG
+
+#ifdef ENABLE_CGAL
+#endif // CGAL error
+#endif // ENABLE_CGAL
+
+#endif // Boost
+#endif // Eigen2
+#endif // MPFR
+#endif // GMP
+
+#endif // OPENSCAD_SKIP_VERSION_CHECK
+