diff --git a/concore_cli/commands/build.py b/concore_cli/commands/build.py
index 83c2056..86fe0bc 100644
--- a/concore_cli/commands/build.py
+++ b/concore_cli/commands/build.py
@@ -138,6 +138,7 @@ def _write_docker_compose(output_path, console, zmq_mode=False):
         compose_lines.append("volumes:")
         for v in sorted(named_volumes):
             compose_lines.append(f"  {v}:")
+            compose_lines.append(f"    name: {_yaml_quote(v)}")
 
     compose_lines.append("")
     compose_lines.append("networks:")
diff --git a/concoredocker.py b/concoredocker.py
index 7388f9a..47f52ca 100644
--- a/concoredocker.py
+++ b/concoredocker.py
@@ -36,7 +36,7 @@
 simtime = 0
 
 def _port_path(base, port_num):
-    return os.path.join(base, str(port_num))
+    return base + str(port_num)
 
 concore_params_file = os.path.join(_port_path(inpath, 1), "concore.params")
 concore_maxtime_file = os.path.join(_port_path(inpath, 1), "concore.maxtime")
diff --git a/demo/sampleJ.graphml b/demo/sampleJ.graphml
new file mode 100644
index 0000000..27a89ae
--- /dev/null
+++ b/demo/sampleJ.graphml
@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://www.yworks.com/xml/schema/graphml/1.1/ygraphml.xsd" xmlns:y="http://www.yworks.com/xml/graphml">
+  <key for="node" id="d6" yfiles.type="nodegraphics"/>
+  <key for="edge" id="d10" yfiles.type="edgegraphics"/>
+  <graph edgedefault="directed" id="1638389982514" projectName="sample">
+    <node id="23fe819b-a16c-43cb-9d94-f3b53d06985f">
+      <data key="d6">
+        <y:ShapeNode>
+          <y:Geometry height="50" width="132" x="100" y="100"/>
+          <y:Fill color="#ffcc00" opacity="1"/>
+          <y:BorderStyle color="#000" width="1"/>
+          <y:NodeLabel>CZ:controller_jl.jl</y:NodeLabel>
+          <y:Shape type="rectangle"/>
+        </y:ShapeNode>
+      </data>
+    </node>
+    <node id="9c5e14c8-1f5c-420e-a72d-46b2efa244a6">
+      <data key="d6">
+        <y:ShapeNode>
+          <y:Geometry height="50" width="100" x="99" y="262"/>
+          <y:Fill color="#ffcc00" opacity="1"/>
+          <y:BorderStyle color="#000" width="1"/>
+          <y:NodeLabel>PZ:pm.py</y:NodeLabel>
+          <y:Shape type="rectangle"/>
+        </y:ShapeNode>
+      </data>
+    </node>
+    <edge id="0" source="23fe819b-a16c-43cb-9d94-f3b53d06985f" target="9c5e14c8-1f5c-420e-a72d-46b2efa244a6">
+      <data key="d10">
+        <y:GenericEdge configuration="com.yworks.bpmn.Connection">
+          <y:LineStyle color="#f44336" width="1" type="solid"/>
+          <y:Arrows source="none" target="delta"/>
+          <y:EdgeLabel>CU</y:EdgeLabel>
+          <y:Path sx="0.0" sy="0.0" tx="0.0" ty="0.0">
+            <y:Point x="99.42283950617283" y="193.5"/>
+          </y:Path>
+        </y:GenericEdge>
+      </data>
+    </edge>
+    <edge id="1" source="9c5e14c8-1f5c-420e-a72d-46b2efa244a6" target="23fe819b-a16c-43cb-9d94-f3b53d06985f">
+      <data key="d10">
+        <y:GenericEdge configuration="com.yworks.bpmn.Connection">
+          <y:LineStyle color="#827717" width="1" type="solid"/>
+          <y:Arrows source="none" target="delta"/>
+          <y:EdgeLabel>PYM</y:EdgeLabel>
+          <y:Path sx="0.0" sy="0.0" tx="0.0" ty="0.0">
+            <y:Point x="122.24371946735148" y="167.84209541286452"/>
+          </y:Path>
+        </y:GenericEdge>
+      </data>
+    </edge>
+  </graph>
+</graphml>
diff --git a/tests/test_compose_generation.py b/tests/test_compose_generation.py
index ba57ce5..81ef087 100644
--- a/tests/test_compose_generation.py
+++ b/tests/test_compose_generation.py
@@ -27,6 +27,13 @@ def test_compose_has_network_section(tmp_path):
     assert "networks:" in content
 
 
+def test_compose_preserves_named_volume(tmp_path):
+    (tmp_path / "run").write_text("docker run --name node1 -v CU:/out1 concore/py &")
+    path = _write_docker_compose(tmp_path, Console(quiet=True))
+    content = path.read_text()
+    assert "  CU:\n    name: 'CU'" in content
+
+
 def test_compose_depends_on_second_service(tmp_path):
     _fake_run_script(
         tmp_path,
diff --git a/tests/test_concoredocker.py b/tests/test_concoredocker.py
index 2d8d8fa..15ff939 100644
--- a/tests/test_concoredocker.py
+++ b/tests/test_concoredocker.py
@@ -44,6 +44,14 @@ def test_returns_default_for_bad_syntax(self, temp_dir):
         assert result == "fallback"
 
 
+class TestDockerPaths:
+    def test_port_path_matches_docker_mounts(self):
+        from concoredocker import _port_path
+
+        assert _port_path("/in", 1) == "/in1"
+        assert _port_path("/out", 2) == "/out2"
+
+
 class TestUnchanged:
     def test_returns_true_when_unchanged(self):
         import concoredocker
@@ -89,9 +97,10 @@ def test_writes_list_with_simtime(self, temp_dir):
         import concoredocker
 
         old_outpath = concoredocker.outpath
-        outdir = os.path.join(temp_dir, "1")
+        outpath = os.path.join(temp_dir, "out")
+        outdir = outpath + "1"
         os.makedirs(outdir)
-        concoredocker.outpath = temp_dir
+        concoredocker.outpath = outpath
         concoredocker.simtime = 5.0
 
         concoredocker.write(1, "testfile", [1.0, 2.0], delta=0)
@@ -105,9 +114,10 @@ def test_writes_with_delta(self, temp_dir):
         import concoredocker
 
         old_outpath = concoredocker.outpath
-        outdir = os.path.join(temp_dir, "1")
+        outpath = os.path.join(temp_dir, "out")
+        outdir = outpath + "1"
         os.makedirs(outdir)
-        concoredocker.outpath = temp_dir
+        concoredocker.outpath = outpath
         concoredocker.simtime = 10.0
 
         concoredocker.write(1, "testfile", [3.0], delta=2)
@@ -126,9 +136,10 @@ def test_reads_and_parses_data(self, temp_dir):
 
         old_inpath = concoredocker.inpath
         old_delay = concoredocker.delay
-        indir = os.path.join(temp_dir, "1")
+        inpath = os.path.join(temp_dir, "in")
+        indir = inpath + "1"
         os.makedirs(indir)
-        concoredocker.inpath = temp_dir
+        concoredocker.inpath = inpath
         concoredocker.delay = 0.001
 
         with open(os.path.join(indir, "data"), "w") as f:
@@ -149,9 +160,10 @@ def test_returns_default_when_file_missing(self, temp_dir):
 
         old_inpath = concoredocker.inpath
         old_delay = concoredocker.delay
-        indir = os.path.join(temp_dir, "1")
+        inpath = os.path.join(temp_dir, "in")
+        indir = inpath + "1"
         os.makedirs(indir)
-        concoredocker.inpath = temp_dir
+        concoredocker.inpath = inpath
         concoredocker.delay = 0.001
 
         concoredocker.s = ""