diff --git a/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.cc b/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.cc
index 144c54bf..ce63bff3 100644
--- a/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.cc
+++ b/src/OpenMesh/Apps/QtViewer/MeshViewerWidgetT.cc
@@ -500,7 +500,7 @@ MeshViewerWidgetT<M>::draw_openmesh(const std::string& _draw_mode)
     for (; strip_it!=strip_last; ++strip_it)
     {
       glDrawElements(GL_TRIANGLE_STRIP, 
-		     strip_it->size(), GL_UNSIGNED_INT, &(*strip_it)[0] );
+          static_cast<GLsizei>(strip_it->size()), GL_UNSIGNED_INT, &(*strip_it)[0] );
     }
 
     glDisableClientState(GL_VERTEX_ARRAY);
@@ -554,7 +554,7 @@ MeshViewerWidgetT<M>::draw_openmesh(const std::string& _draw_mode)
       glColorPointer(3, GL_UNSIGNED_BYTE, 0, mesh_.vertex_colors());
     }
 
-    glDrawArrays( GL_POINTS, 0, mesh_.n_vertices() );
+    glDrawArrays( GL_POINTS, 0, static_cast<GLsizei>(mesh_.n_vertices()) );
     glDisableClientState(GL_VERTEX_ARRAY);
     glDisableClientState(GL_COLOR_ARRAY);
   }
diff --git a/src/OpenMesh/Core/Geometry/NormalConeT.cc b/src/OpenMesh/Core/Geometry/NormalConeT.cc
index 6e3ed3a8..40f7a821 100644
--- a/src/OpenMesh/Core/Geometry/NormalConeT.cc
+++ b/src/OpenMesh/Core/Geometry/NormalConeT.cc
@@ -121,16 +121,16 @@ merge(const NormalConeT& _cone)
 {
   Scalar dotp = (center_normal_ | _cone.center_normal_);
 
-  if (fabs(dotp) < 0.99999)
+  if (fabs(dotp) < 0.99999f)
   {
     // new angle
     Scalar centerAngle = acos(dotp);
     Scalar minAngle    = std::min(-angle(), centerAngle - _cone.angle());
     Scalar maxAngle    = std::max( angle(), centerAngle + _cone.angle());
-    angle_     = (maxAngle - minAngle) * 0.5;
+    angle_     = (maxAngle - minAngle) * Scalar(0.5f);
 
     // axis by SLERP
-    Scalar axisAngle = 0.5*(minAngle + maxAngle);
+    Scalar axisAngle =  Scalar(0.5f) * (minAngle + maxAngle);
     center_normal_ = ((center_normal_ * sin(centerAngle-axisAngle)
 		                   + _cone.center_normal_ * sin(axisAngle))
 		                    / sin(centerAngle));
@@ -138,12 +138,12 @@ merge(const NormalConeT& _cone)
   else
   {
     // axes point in same direction
-    if (dotp > 0.0)
+    if (dotp > 0.0f)
       angle_ = std::max(angle_, _cone.angle_);
 
     // axes point in opposite directions
     else
-      angle_ = 2.0 * M_PI;
+      angle_ =  Scalar(2.0f * M_PI);
   }
 }
 
diff --git a/src/OpenMesh/Tools/Decimater/ModHausdorffT.cc b/src/OpenMesh/Tools/Decimater/ModHausdorffT.cc
index d3daccc8..26fc6e93 100644
--- a/src/OpenMesh/Tools/Decimater/ModHausdorffT.cc
+++ b/src/OpenMesh/Tools/Decimater/ModHausdorffT.cc
@@ -94,7 +94,7 @@ distPointTriangleSquared( const Point& _p,
 
   Point v0p = _p - _v0;
   Point t = v0p % n;
-  double  s01, s02, s12;
+  typename Point::value_type  s01, s02, s12;
   const double a = (t | v0v2) * -invD;
   const double b = (t | v0v1) * invD;
 
diff --git a/src/OpenMesh/Tools/Decimater/ModRoundnessT.hh b/src/OpenMesh/Tools/Decimater/ModRoundnessT.hh
index 05784839..73fb35dc 100644
--- a/src/OpenMesh/Tools/Decimater/ModRoundnessT.hh
+++ b/src/OpenMesh/Tools/Decimater/ModRoundnessT.hh
@@ -125,7 +125,7 @@ class ModRoundnessT : public ModBaseT<MeshT>
     typename Mesh::FaceHandle               fhC, fhB;
     Vec3f                                   B,C;
 
-    if ( min_r_ < 0.0 ) // continues mode
+    if ( min_r_ < 0.0f ) // continues mode
     {
       C   = vector_cast<Vec3f>(Base::mesh().point( Base::mesh().to_vertex_handle(*voh_it)));
       fhC = Base::mesh().face_handle( *voh_it );
@@ -196,17 +196,17 @@ public: // specific methods
 
     Vec3f A,B,C;
 
-    A = Vec3f(             0, 0,           0);
-    B = Vec3f( 2*cos(_angle), 0,           0);
-    C = Vec3f(   cos(_angle), sin(_angle), 0);
+    A = Vec3f(               0.0f, 0.0f,           0.0f);
+    B = Vec3f( 2.0f * cos(_angle), 0.0f,           0.0f);
+    C = Vec3f(        cos(_angle), sin(_angle),    0.0f);
 
     double r1 = roundness(A,B,C);
 
     _angle = float(0.5 * ( M_PI - _angle ));
 
-    A = Vec3f(             0, 0,           0);
-    B = Vec3f( 2*cos(_angle), 0,           0);
-    C = Vec3f(   cos(_angle), sin(_angle), 0);
+    A = Vec3f(             0.0f, 0.0f,           0.0f);
+    B = Vec3f( 2.0f*cos(_angle), 0.0f,           0.0f);
+    C = Vec3f(      cos(_angle), sin(_angle),    0.0f);
 
     double r2 = roundness(A,B,C);
 
diff --git a/src/OpenMesh/Tools/Utils/StripifierT.cc b/src/OpenMesh/Tools/Utils/StripifierT.cc
index a83d136d..44162a86 100644
--- a/src/OpenMesh/Tools/Utils/StripifierT.cc
+++ b/src/OpenMesh/Tools/Utils/StripifierT.cc
@@ -75,7 +75,7 @@ StripifierT<Mesh>::
 }
 
 template <class Mesh>
-unsigned int
+size_t
 StripifierT<Mesh>::
 stripify()
 {
@@ -107,7 +107,7 @@ build_strips()
 {
   Strip                           experiments[3];
   typename Mesh::HalfedgeHandle   h[3];
-  unsigned int                    best_idx, best_length, length;
+  size_t                          best_length,length , best_idx;
   FaceHandles                     faces[3];
   typename FaceHandles::iterator  fh_it, fh_end;
   typename Mesh::FaceIter         f_it, f_end=mesh_.faces_end();
@@ -148,8 +148,9 @@ build_strips()
 
 
     // build 3 strips, take best one
-    best_length = best_idx = 0;
-    for (unsigned int i=0; i<3; ++i)
+    best_length = 0;
+    best_idx    = 0;
+    for (size_t i=0; i<3; ++i)
     {
       build_strip(h[i], experiments[i], faces[i]);
       if ((length = experiments[i].size()) > best_length)
diff --git a/src/OpenMesh/Tools/Utils/StripifierT.hh b/src/OpenMesh/Tools/Utils/StripifierT.hh
index 579eb9cb..fc009a9b 100644
--- a/src/OpenMesh/Tools/Utils/StripifierT.hh
+++ b/src/OpenMesh/Tools/Utils/StripifierT.hh
@@ -92,7 +92,7 @@ public:
   ~StripifierT();
 
   /// Compute triangle strips, returns number of strips
-  unsigned int stripify();
+  size_t stripify();
 
   /// delete all strips
   void clear() { Strips().swap(strips_); }