diff --git a/lib/Slic3r/TriangleMesh.pm b/lib/Slic3r/TriangleMesh.pm
index 216e28c1a..b95521274 100644
--- a/lib/Slic3r/TriangleMesh.pm
+++ b/lib/Slic3r/TriangleMesh.pm
@@ -196,7 +196,9 @@ sub make_loops {
         # if two lines start at this point, one being a 'top' facet edge and the other being a 'bottom' one,
         # then remove the top one and those following it (removing the top or the bottom one is an arbitrary
         # choice)
-        if (@lines_starting_here == 2 && join('', sort map $_->[I_FACET_EDGE], @lines_starting_here) eq FE_TOP.FE_BOTTOM) {
+        # The "// ''" on the next line avoids uninitialized value errors mentioned in issue #357 but these
+        # errors occur on fixed models so the root cause still needs to be found
+        if (@lines_starting_here == 2 && join('', sort map $_->[I_FACET_EDGE] // '', @lines_starting_here) eq FE_TOP.FE_BOTTOM) {
             my @to_remove = grep $_->[I_FACET_EDGE] == FE_TOP, @lines_starting_here;
             while (!grep defined $_->[I_B_ID] && $_->[I_B_ID] == $to_remove[-1]->[I_B_ID] && $_ ne $to_remove[-1], @lines) {
                 push @to_remove, grep defined $_->[I_A_ID] && $_->[I_A_ID] == $to_remove[-1]->[I_B_ID], @lines;