diff --git a/src/wings_we_build.erl b/src/wings_we_build.erl
index 13624363..a0113979 100644
--- a/src/wings_we_build.erl
+++ b/src/wings_we_build.erl
@@ -508,7 +508,7 @@ find_hard_edges(Face, FlatNormal, SmoothNs0, EdgeNs, {He0, Possible0}, We) ->
                                     #edge{lf = Face, vs = V, ltsu = Next} -> {VNS, Next};
                                     #edge{rf = Face, ve = V, rtsu = Next} -> {VNE, Next}
                                 end,
-                  case e3d_vec:dist_sqr(VN, FlatNormal) < ?EPSILON of
+                  try e3d_vec:dist_sqr(VN, FlatNormal) < ?EPSILON of
                       true ->
                           %% io:format("HE: V=~3w F=~3w Es: ~w ~w~n", [V, Face, Edge, Other]),
                           {SmoothNs, [Edge, Other|He], Possible};
@@ -522,6 +522,10 @@ find_hard_edges(Face, FlatNormal, SmoothNs0, EdgeNs, {He0, Possible0}, We) ->
                                   %% io:format("    Calc: ~s Imp: ~s Face: ~s~n", [e3d_vec:format(SN), e3d_vec:format(VN), e3d_vec:format(FlatNormal)]),
                                   {SmoothNs, He, [V|Possible]}
                           end
+                  catch error:function_clause ->
+                          %% Missing vertex normal, assume face-normal or smooth?
+                          %% Currently we make it smooth
+                          {SmoothNs, He, Possible}
                   end
           end,
     {[], He, Poss} = wings_face:fold(Fun, {lists:reverse(SmoothNs0), He0, Possible0}, Face, We),
@@ -548,11 +552,14 @@ find_he_from_vertex([], _, HeAcc, _) ->
 pick_edges({N1, Edge, NextFace}, Tree0, Acc) ->
     try gb_trees:take(NextFace, Tree0) of
         {{N2, _, _} = Next, Tree} ->
-            case e3d_vec:dist_sqr(N1,N2) < ?EPSILON of
+            try e3d_vec:dist_sqr(N1,N2) < ?EPSILON of
                 true  -> pick_edges(Next, Tree, Acc);
                 false -> pick_edges(Next, Tree, [Edge|Acc])
+            catch error:function_clause ->
+                    %% Vertex normals assume smooth normal
+                    pick_edges(Next, Tree, Acc)
             end
-    catch _:_ ->
+    catch _E:_R ->
             Acc
     end.