diff --git a/wrap/io_trimesh/export_ctm.h b/wrap/io_trimesh/export_ctm.h
index 9befd082..54faee9c 100644
--- a/wrap/io_trimesh/export_ctm.h
+++ b/wrap/io_trimesh/export_ctm.h
@@ -44,7 +44,7 @@ namespace vcg {
                     std::vector<CTMfloat> aColors(aVertCount*4);
                     std::vector<CTMfloat> aQuality(aVertCount*4);
                     std::vector<CTMuint> aIndices(aTriCount*3);
-
+                    int err;
                     CTMcontext context;
                     // Create a new exporter context
                     context = ctmNewContext(CTM_EXPORT);
@@ -54,26 +54,32 @@ namespace vcg {
                       ctmVertexPrecision(context, relativePrecision);
                     }
                     // Prepare vertex and faces
-                    for(int i=0;i<aVertCount;++i)
+                    for(unsigned int i=0;i<aVertCount;++i)
                     {
                         aVertices[i*3+0]=m.vert[i].P()[0];
                         aVertices[i*3+1]=m.vert[i].P()[1];
                         aVertices[i*3+2]=m.vert[i].P()[2];
                     }
-                    for(int i=0;i<aTriCount;++i)
+                    for(unsigned int i=0;i<aTriCount;++i)
                     {
                         aIndices[i*3+0]=m.face[i].V(0)-&*m.vert.begin();
                         aIndices[i*3+1]=m.face[i].V(1)-&*m.vert.begin();
                         aIndices[i*3+2]=m.face[i].V(2)-&*m.vert.begin();
                     }
+                    if(aTriCount==0)
+                    {
+                      aIndices.resize(3,0);
+                      aTriCount=1;
+                    }
 
                     // Define our mesh representation to OpenCTM
                     ctmDefineMesh(context, &*aVertices.begin(), aVertCount, &*aIndices.begin(), aTriCount, NULL);
-
+                    err=ctmGetError(context);
+                    if(err) return err;
                     if( tri::HasPerVertexColor(m)   && (mask & io::Mask::IOM_VERTCOLOR))
                     {
                         aColors.resize(aVertCount*4);
-                        for(int i=0;i<aVertCount;++i)
+                        for(unsigned int i=0;i<aVertCount;++i)
                         {
                             aColors[i*4+0]=(float)(m.vert[i].C()[0])/255.0f;
                             aColors[i*4+1]=(float)(m.vert[i].C()[1])/255.0f;
@@ -85,7 +91,7 @@ namespace vcg {
                     if( tri::HasPerVertexQuality(m)   && (mask & io::Mask::IOM_VERTQUALITY))
                     {
                         aQuality.resize(aVertCount*4,0);
-                        for(int i=0;i<aVertCount;++i)
+                        for(unsigned int i=0;i<aVertCount;++i)
                         {
                             aQuality[i*4+0]=m.vert[i].Q();
                         }
@@ -94,9 +100,11 @@ namespace vcg {
 
                     // Save the OpenCTM file
                     ctmSave(context, filename);
+                    err=ctmGetError(context);
+                    if(err) return err;
                     // Free the context
                     ctmFreeContext(context);
-                    return 0;
+                    return err;
                 }
                 /*
             returns mask of capability one define with what are the saveable information of the format.
@@ -114,8 +122,8 @@ namespace vcg {
 
                 static const char *ErrorMsg(int error)
                 {
-                    if(error==-1) return "unable to open file";
-                    return "Ok, no errors";
+                    if(error==0) return "Ok, no errors";
+                    else return ctmErrorString((CTMenum)error);
                 }
             };
         } // end namespace io
diff --git a/wrap/io_trimesh/import_ctm.h b/wrap/io_trimesh/import_ctm.h
index cced1f0e..6a4b257b 100644
--- a/wrap/io_trimesh/import_ctm.h
+++ b/wrap/io_trimesh/import_ctm.h
@@ -86,7 +86,7 @@ static const char* ErrorMsg(int error)
 };
 
 
-static int Open( OpenMeshType &m, const char * filename, int &loadmask, CallBackPos *cb=0)
+static int Open( OpenMeshType &m, const char * filename, int &loadmask, CallBackPos */*cb*/=0)
 {
     CTMcontext context;
 
@@ -106,14 +106,14 @@ static int Open( OpenMeshType &m, const char * filename, int &loadmask, CallBack
     // Extract colors
     m.Clear();
     Allocator<OpenMeshType>::AddVertices(m, vertCount);
-    for(int i=0;i<vertCount;++i)
+    for(unsigned int i=0;i<vertCount;++i)
         m.vert[i].P()=Point3f(vertices[i*3+0],vertices[i*3+1],vertices[i*3+2]);
 
     CTMenum colorAttrib = ctmGetNamedAttribMap(context,"Color");
     if(colorAttrib != CTM_NONE)
     {
       const CTMfloat *colors = ctmGetFloatArray(context,colorAttrib);
-      for(int i=0;i<vertCount;++i)
+      for(unsigned int i=0;i<vertCount;++i)
           m.vert[i].C()=Color4b(colors[i*4+0]*255,colors[i*4+1]*255,colors[i*4+2]*255,colors[i*4+3]*255);
       loadmask |= Mask::IOM_VERTCOLOR;
     }
@@ -122,13 +122,18 @@ static int Open( OpenMeshType &m, const char * filename, int &loadmask, CallBack
     if(qualityAttrib != CTM_NONE)
     {
       const CTMfloat *qualities = ctmGetFloatArray(context,colorAttrib);
-      for(int i=0;i<vertCount;++i)
+      for(unsigned int i=0;i<vertCount;++i)
           m.vert[i].Q()=qualities[i*4+0];
       loadmask |= Mask::IOM_VERTQUALITY;
     }
 
+    if(triCount==1)
+    {
+      if(indices[0]==0 && indices[1]==0 && indices[2]==0)
+        triCount=0;
+    }
     Allocator<OpenMeshType>::AddFaces(m, triCount);
-    for(int i=0;i<triCount;++i)
+    for(unsigned int i=0;i<triCount;++i)
     {
         m.face[i].V(0)=&m.vert[indices[i*3+0]];
         m.face[i].V(1)=&m.vert[indices[i*3+1]];
@@ -139,8 +144,7 @@ static int Open( OpenMeshType &m, const char * filename, int &loadmask, CallBack
     }
 
     int result = E_NOERROR;
-
-	return result;
+    return result;
 } // end of Open