diff --git a/common.scad b/common.scad
index db4f3bb..570ff8e 100644
--- a/common.scad
+++ b/common.scad
@@ -353,6 +353,7 @@ function segs(r) =
 // Arguments:
 //   $children = number of children the module has.  
 module no_children(count) {
+  assert($children==0, "Module no_children() does not support child modules");
   assert(count==0, str("Module ",parent_module(1),"() does not support child modules"));
 }
 
@@ -377,6 +378,7 @@ function _valstr(x) =
 //   expected = The value that was expected.
 //   info = Extra info to print out to make the error clearer.
 module assert_approx(got, expected, info) {
+    no_children($children);
     if (!approx(got, expected)) {
         echo();
         echo(str("EXPECT: ", _valstr(expected)));
@@ -404,6 +406,7 @@ module assert_approx(got, expected, info) {
 //   expected = The value that was expected.
 //   info = Extra info to print out to make the error clearer.
 module assert_equal(got, expected, info) {
+    no_children($children);
     if (got != expected || (is_nan(got) && is_nan(expected))) {
         echo();
         echo(str("EXPECT: ", _valstr(expected)));
diff --git a/polyhedra.scad b/polyhedra.scad
index 3231606..13cbe54 100644
--- a/polyhedra.scad
+++ b/polyhedra.scad
@@ -652,7 +652,7 @@ function regular_polyhedron_info(
     let(
         entry = (
             name == "trapezohedron"? (
-                trapezohedron(faces=faces, side=side, longside=longside, h=h, r=r)
+                _trapezohedron(faces=faces, side=side, longside=longside, h=h, r=r)
             ) : (
                 _polyhedra_[!is_undef(index)?
                     indexlist[index] :
@@ -671,7 +671,7 @@ function regular_polyhedron_info(
             ) / entry[edgelen]
         ),
         face_triangles = hull(entry[vertices]),
-        faces_normals_vertices = stellate_faces(
+        faces_normals_vertices = _stellate_faces(
             entry[edgelen], stellate, entry[vertices],
             entry[facevertices]==[3]?
                 [face_triangles, [for(face=face_triangles) _facenormal(entry[vertices],face)]] :
@@ -713,11 +713,7 @@ function regular_polyhedron_info(
     assert(false, str("Unknown info type '",info,"' requested"));
 
 
-
-/// hull solution fails due to roundoff
-/// either cross product or just rotate to
-///
-function stellate_faces(scalefactor,stellate,vertices,faces_normals) =
+function _stellate_faces(scalefactor,stellate,vertices,faces_normals) =
     (stellate == false || stellate == 0)? concat(faces_normals,[vertices]) :
     let(
         faces = [for(face=faces_normals[0]) select(face,hull(select(vertices,face)))],
@@ -730,8 +726,8 @@ function stellate_faces(scalefactor,stellate,vertices,faces_normals) =
     ) [newfaces, normals, allpts];
 
 
-function trapezohedron(faces, r, side, longside, h, d) =
-    assert(faces%2==0, "Number of faces must be even")
+function _trapezohedron(faces, r, side, longside, h, d) =
+    assert(faces%2==0, "Must set 'faces' to an even number for trapezohedron")
     let(
         r = get_radius(r=r, d=d, dflt=1),
         N = faces/2,
diff --git a/strings.scad b/strings.scad
index cc0713b..5e34fd9 100644
--- a/strings.scad
+++ b/strings.scad
@@ -701,7 +701,9 @@ function str_format(fmt, vals, use_nbsp=false) =
 //   echofmt("{:-10s}{:.3f}", ["plecostamus",27.43982]);  // ECHO: "plecostamus27.440"
 //   echofmt("{:-10.9s}{:.3f}", ["plecostamus",27.43982]);  // ECHO: "plecostam 27.440"
 function echofmt(fmt, vals, use_nbsp=false) = echo(str_format(fmt,vals,use_nbsp));
-module echofmt(fmt, vals, use_nbsp=false) echo(str_format(fmt,vals,use_nbsp));
-
+module echofmt(fmt, vals, use_nbsp=false) {
+   no_children($children);
+   echo(str_format(fmt,vals,use_nbsp));
+}
 
 // vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap
diff --git a/structs.scad b/structs.scad
index e7effb4..1e9f321 100644
--- a/structs.scad
+++ b/structs.scad
@@ -101,6 +101,7 @@ function struct_echo(struct,name="") =
     undef;
 
 module struct_echo(struct,name="") {
+    no_children($children);
     dummy = struct_echo(struct,name);
 }
 
diff --git a/tests/test_transforms.scad b/tests/test_transforms.scad
index a44e47c..3fb044b 100644
--- a/tests/test_transforms.scad
+++ b/tests/test_transforms.scad
@@ -232,7 +232,7 @@ module test_rot() {
         assert_equal(rot(a,p=pts2d), pts2d, info=str("rot(",a,",p=...), 2D"));
         assert_equal(rot(a,p=pts3d), pts3d, info=str("rot(",a,",p=...), 3D"));
     }
-    assert_equal(rot(90), [[0,-1,0,0],[1,0,0,0],[0,0,1,0],[0,0,0,1]])
+    assert_equal(rot(90), [[0,-1,0,0],[1,0,0,0],[0,0,1,0],[0,0,0,1]]);
     for (a=angs) {
         assert_equal(rot(a), affine3d_zrot(a), info=str("Z angle (only) = ",a));
         assert_equal(rot([a,0,0]), affine3d_xrot(a), info=str("X angle = ",a));
diff --git a/version.scad b/version.scad
index 6e4605f..bdbdafa 100644
--- a/version.scad
+++ b/version.scad
@@ -8,7 +8,7 @@
 //////////////////////////////////////////////////////////////////////
 
 
-BOSL_VERSION = [2,0,414];
+BOSL_VERSION = [2,0,415];
 
 
 // Section: BOSL Library Version Functions
@@ -49,6 +49,7 @@ function bosl_version_str() = version_to_str(BOSL_VERSION);
 // Description:
 //   Given a version as a list, number, or string, asserts that the currently installed BOSL library is at least the given version.
 module bosl_required(target) {
+    no_children($children);
     assert(
         version_cmp(bosl_version(), target) >= 0,
         str(
diff --git a/vnf.scad b/vnf.scad
index b0a5607..085c281 100644
--- a/vnf.scad
+++ b/vnf.scad
@@ -348,7 +348,8 @@ function vnf_vertex_array(
 //   orient = Vector to rotate top towards, after spin.  See [orient](attachments.scad#orient).  Default: `UP`
 module vnf_polyhedron(vnf, convexity=2, extent=true, cp=[0,0,0], anchor="origin", spin=0, orient=UP) {
     vnf = is_vnf_list(vnf)? vnf_merge(vnf) : vnf;
-    attachable(anchor,spin,orient, vnf=vnf, cp=cp, extent=extent) {
+    cp = is_def(cp) ? cp : vnf_centroid(vnf);
+    attachable(anchor,spin,orient, vnf=vnf, extent=extent, cp=cp) {
         polyhedron(vnf[0], vnf[1], convexity=convexity);
         children();
     }