diff --git a/modules/geom/CMakeLists.txt b/modules/geom/CMakeLists.txt
index 6955f55f9b8d0237224a2d4aab25aa3b5310003d..f6f5287df953f3865c88a43146f0acbfe9afee3f 100644
--- a/modules/geom/CMakeLists.txt
+++ b/modules/geom/CMakeLists.txt
@@ -1,2 +1,3 @@
 add_subdirectory(src)
+add_subdirectory(tests)
 add_subdirectory(pymod)
\ No newline at end of file
diff --git a/modules/geom/src/composite3_op.cc b/modules/geom/src/composite3_op.cc
index 1c5b699d201c52c9ecdf3f57d2d17441aaca854a..271c4bec84458ae9c784c12afa952e0c21a71ea0 100644
--- a/modules/geom/src/composite3_op.cc
+++ b/modules/geom/src/composite3_op.cc
@@ -92,8 +92,9 @@ Real Distance(const Plane& p, const Vec3& v)
 
 bool IsOnLine(const Line3& l, const Vec3& v, Real ephilon)
 {
-  Vec3 tmp=CompDivide(v-l.GetOrigin(),l.GetDirection());
-  return std::fabs(tmp[0]-tmp[1])<ephilon && std::fabs(tmp[0]-tmp[2])<ephilon;
+  Vec3 s=v-l.GetOrigin();
+  Vec3 s_on_line=Dot(s, l.GetDirection())*l.GetDirection();
+  return Length2(s-s_on_line)<(ephilon*ephilon);
 }
 bool IsInPlane(const Plane& p,  const Line3& l,Real ephilon)
 {
diff --git a/modules/geom/tests/CMakeLists.txt b/modules/geom/tests/CMakeLists.txt
new file mode 100644
index 0000000000000000000000000000000000000000..3235335a246b489305df2d14255d9c0ff2231716
--- /dev/null
+++ b/modules/geom/tests/CMakeLists.txt
@@ -0,0 +1,6 @@
+set(GEOM_UNITTESTS
+  test_composite3.cc
+  tests.cc
+)
+
+ost_unittest(geom "${GEOM_UNITTESTS}")
diff --git a/modules/geom/tests/test_composite3.cc b/modules/geom/tests/test_composite3.cc
new file mode 100644
index 0000000000000000000000000000000000000000..88dd739d76e5927342dda1e0d07350d7e49692e8
--- /dev/null
+++ b/modules/geom/tests/test_composite3.cc
@@ -0,0 +1,54 @@
+//------------------------------------------------------------------------------
+// This file is part of the OpenStructure project <www.openstructure.org>
+//
+// Copyright (C) 2008-2011 by the OpenStructure authors
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License as published by the Free
+// Software Foundation; either version 3.0 of the License, or (at your option)
+// any later version.
+// This library is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this library; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+//------------------------------------------------------------------------------
+
+#include <ost/geom/geom.hh>
+
+#define BOOST_TEST_DYN_LINK
+#include <boost/test/unit_test.hpp>
+
+using namespace geom;
+
+BOOST_AUTO_TEST_SUITE( geom )
+
+
+BOOST_AUTO_TEST_CASE(line_init)
+{
+  Line3 line(geom::Vec3(0,0,0), geom::Vec3(2,0,0));
+  BOOST_CHECK_EQUAL(geom::Length(line.GetDirection()), 1.0);
+}
+
+BOOST_AUTO_TEST_CASE(is_on_line)
+{
+  Line3 line(geom::Vec3(0,0,0), geom::Vec3(1,0,0));
+  BOOST_CHECK(IsOnLine(line, geom::Vec3(0.5,0.0,0.0)));
+  BOOST_CHECK(IsOnLine(line, geom::Vec3(1.0,0.0,0.0)));
+  BOOST_CHECK(IsOnLine(line, geom::Vec3(0.0,0.0,0.0)));
+  BOOST_CHECK(IsOnLine(line, geom::Vec3(-5,0.0,0.0)));
+  BOOST_CHECK(IsOnLine(line, geom::Vec3(10.0,0.0,0.0)));
+  BOOST_CHECK(!IsOnLine(line, geom::Vec3(0.5,0.1,0.0)));
+  BOOST_CHECK(!IsOnLine(line, geom::Vec3(1.0,0.0,0.1)));
+  
+  line=Line3(geom::Vec3(1,0,0), geom::Vec3(1,1,1));
+  for (int i=-10; i<10; ++i) {
+    BOOST_CHECK(IsOnLine(line, line.At(i), 1e-6));
+  }
+  BOOST_CHECK(!IsOnLine(line, geom::Vec3(1,2,2.1), 1e-6));
+}
+
+BOOST_AUTO_TEST_SUITE_END()
\ No newline at end of file
diff --git a/modules/geom/tests/tests.cc b/modules/geom/tests/tests.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fbce7b185d7ce437b2832e5468bba0226a4da83b
--- /dev/null
+++ b/modules/geom/tests/tests.cc
@@ -0,0 +1,22 @@
+//------------------------------------------------------------------------------
+// This file is part of the OpenStructure project <www.openstructure.org>
+//
+// Copyright (C) 2008-2011 by the OpenStructure authors
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License as published by the Free
+// Software Foundation; either version 3.0 of the License, or (at your option)
+// any later version.
+// This library is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this library; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+//------------------------------------------------------------------------------
+#define BOOST_TEST_DYN_LINK
+#define BOOST_TEST_MODULE geom
+#include <boost/test/unit_test.hpp>
+