diff --git a/edgehog/init_extant_synteny_graphs.py b/edgehog/init_extant_synteny_graphs.py
index 890f9cf..b3c1181 100644
--- a/edgehog/init_extant_synteny_graphs.py
+++ b/edgehog/init_extant_synteny_graphs.py
@@ -101,7 +101,12 @@ def get_representative_hog_for_gene(ham, hogxml_entries):
 def assign_extant_synteny(genome, gene_dict, ham, orient_edges): 
     graph = nx.Graph(genome=genome)
     contiguity_dict = dict()
-    gene_keys = list(gene_dict.keys())
+    # gffs are not necessarily sorted: order the genes by contig (in order of first appearance in the gff)
+    # and by genomic coordinates on the contig
+    contig_rank = dict()
+    for contig, _ in gene_dict:
+        contig_rank.setdefault(contig, len(contig_rank))
+    gene_keys = sorted(gene_dict, key=lambda key: (contig_rank[key[0]], gene_dict[key]['start'], gene_dict[key]['end']))
 
     # find first gene with hogxml_entries, i.e. that is reported in orthoxml
     for first, gene_key in enumerate(gene_keys):
@@ -110,7 +115,8 @@ def assign_extant_synteny(genome, gene_dict, ham, orient_edges):
     else:
         raise ValueError('No gene with hogxml_entries found in genome %s' % genome.name)
 
-    old_contig = gene_keys[first][0]
+    old_key = gene_keys[first]
+    old_contig = old_key[0]
     hogxml_entries = gene_dict[gene_keys[first]]['hogxml_entries']
     old_gene = get_representative_hog_for_gene(ham, hogxml_entries)
     graph.add_node(old_gene, **gene_dict[gene_keys[first]], contig=old_contig)
@@ -124,7 +130,8 @@ def assign_extant_synteny(genome, gene_dict, ham, orient_edges):
                 # connect genes only if they are on the same contig
                 graph.add_edge(old_gene, gene, weight=1, unidirectional=0, convergent=0, divergent=0, children=[None], extant_descendants=[None])
                 if orient_edges:
-                    old_gene_strand = gene_dict[gene_keys[i-1]]['strand']
+                    # strand of the previous gene in the orthoxml, not of a skipped gene in between
+                    old_gene_strand = gene_dict[old_key]['strand']
                     gene_strand = gene_dict[gene_keys[i]]['strand']
                     try:
                         if old_gene_strand == gene_strand:
@@ -135,7 +142,7 @@ def assign_extant_synteny(genome, gene_dict, ham, orient_edges):
                             graph[old_gene][gene]['divergent'] = 1
                     except:
                         pass
-            old_gene, old_contig = gene, contig
+            old_gene, old_contig, old_key = gene, contig, gene_keys[i]
     # for cc in nx.connected_components(graph):
     #     if len(cc > 1):
     #         for i in range(0, len(cc)):
diff --git a/pyproject.toml b/pyproject.toml
index 0a956e0..fd85426 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "edgehog"
-version = "0.1.10"
+version = "0.1.11"
 description = "Infering ancestral synteny with hierarchical orthologous groups"
 authors = [
    {name="Charles Bernard", email="charles.bernard@unil.ch"},
diff --git a/tests/test_extant_graphs.py b/tests/test_extant_graphs.py
index 38e20c7..36a2521 100644
--- a/tests/test_extant_graphs.py
+++ b/tests/test_extant_graphs.py
@@ -122,7 +122,6 @@ def test_find_gff_files(tmp_path):
 # features by contig and start coordinate (read_gff.py:100-117,
 # init_extant_synteny_graphs.py:88).
 
-@pytest.mark.xfail(strict=True, reason="#6: unsorted GFFs give wrong adjacencies")
 def test_unsorted_gff(tmp_path):
     gff = write_gff(tmp_path / "SP.gff",
                     gene("chr1", 100, 200, "+", "g1", "p1"),
@@ -131,7 +130,6 @@ def test_unsorted_gff(tmp_path):
     assert edge_set(build_graph(gff, ["p1", "p2", "p3"])) == edges("p1-p2", "p2-p3")
 
 
-@pytest.mark.xfail(strict=True, reason="#6: contigs interleaved in the GFF lose adjacencies")
 def test_interleaved_contigs(tmp_path):
     gff = write_gff(tmp_path / "SP.gff",
                     gene("chr1", 100, 200, "+", "g1", "p1"),
@@ -144,7 +142,6 @@ def test_interleaved_contigs(tmp_path):
 # previous linked gene if a gene missing from the orthoXML lies in between
 # (init_extant_synteny_graphs.py:111).
 
-@pytest.mark.xfail(strict=True, reason="#7: orientation uses the strand of a skipped gene")
 def test_orientation_ignores_skipped_gene(tmp_path):
     gff = write_gff(tmp_path / "SP.gff",
                     gene("chr1", 100, 200, "+", "g1", "p1"),
diff --git a/uv.lock b/uv.lock
index 8451e22..947ce2e 100644
--- a/uv.lock
+++ b/uv.lock
@@ -333,7 +333,7 @@ wheels = [
 
 [[package]]
 name = "edgehog"
-version = "0.1.10"
+version = "0.1.11"
 source = { editable = "." }
 dependencies = [
     { name = "ete3" },