diff --git a/lib/Slic3r/TriangleMesh.pm b/lib/Slic3r/TriangleMesh.pm
index d830ba54c..0f5df9a4e 100644
--- a/lib/Slic3r/TriangleMesh.pm
+++ b/lib/Slic3r/TriangleMesh.pm
@@ -152,9 +152,9 @@ sub check_manifoldness {
     my ($first_bad_edge_id) =
         grep { @{ $self->edges_facets->[$_] } != 2 } 0..$#{$self->edges_facets};
     if (defined $first_bad_edge_id) {
-        warn sprintf "Warning: The input file contains a hole near edge %f-%f (not manifold). "
+        warn sprintf "Warning: The input file contains a hole near edge %f,%f,%f-%f,%f,%f (not manifold). "
             . "You might want to repair it and retry, or to check the resulting G-code before printing anyway.\n",
-            @{$self->edges->[$first_bad_edge_id]};
+            map @{$self->vertices->[$_]}, @{$self->edges->[$first_bad_edge_id]};
         return 0;
     }
     return 1;