diff --git a/Bonsai.Configuration/NativeMethods.cs b/Bonsai.Configuration/NativeMethods.cs
index 53fb56fa..62470930 100644
--- a/Bonsai.Configuration/NativeMethods.cs
+++ b/Bonsai.Configuration/NativeMethods.cs
@@ -1,5 +1,4 @@
-using System;
-using System.Runtime.InteropServices;
+using System.Runtime.InteropServices;
 
 namespace Bonsai.Configuration
 {
diff --git a/Bonsai.Configuration/ScriptExtensions.cs b/Bonsai.Configuration/ScriptExtensions.cs
index de7f091b..35a574ed 100644
--- a/Bonsai.Configuration/ScriptExtensions.cs
+++ b/Bonsai.Configuration/ScriptExtensions.cs
@@ -1,5 +1,4 @@
 using NuGet.Configuration;
-using NuGet.Packaging;
 using NuGet.Versioning;
 using System;
 using System.Collections.Generic;
diff --git a/Bonsai.Editor.Tests/EditorHelper.cs b/Bonsai.Editor.Tests/EditorHelper.cs
index ef97a1c7..522627bd 100644
--- a/Bonsai.Editor.Tests/EditorHelper.cs
+++ b/Bonsai.Editor.Tests/EditorHelper.cs
@@ -25,6 +25,14 @@ internal static ExpressionBuilderGraph CreateEditorGraph(params string[] values)
             return graph.ToInspectableGraph();
         }
 
+        internal static TBuilder FindExpressionBuilder<TBuilder>(this ExpressionBuilderGraph workflow) where TBuilder : class
+        {
+            return (from node in workflow
+                    let builder = node.Value as TBuilder
+                    where builder != null
+                    select builder).FirstOrDefault();
+        }
+
         internal static GraphNode FindNode(this WorkflowEditor editor, string name)
         {
             var node = editor.Workflow.First(n => ExpressionBuilder.GetElementDisplayName(n.Value) == name);
diff --git a/Bonsai.Editor.Tests/NestedSubscribeSubjectWithClosestRedefinition.bonsai b/Bonsai.Editor.Tests/NestedSubscribeSubjectWithClosestRedefinition.bonsai
new file mode 100644
index 00000000..6c529d8d
--- /dev/null
+++ b/Bonsai.Editor.Tests/NestedSubscribeSubjectWithClosestRedefinition.bonsai
@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="utf-8"?>
+<WorkflowBuilder Version="2.8.1"
+                 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                 xmlns:rx="clr-namespace:Bonsai.Reactive;assembly=Bonsai.Core"
+                 xmlns="https://bonsai-rx.org/2018/workflow">
+  <Workflow>
+    <Nodes>
+      <Expression xsi:type="Combinator">
+        <Combinator xsi:type="IntProperty">
+          <Value>8</Value>
+        </Combinator>
+      </Expression>
+      <Expression xsi:type="rx:PublishSubject">
+        <Name>Values</Name>
+      </Expression>
+      <Expression xsi:type="SubscribeSubject">
+        <Name>Values</Name>
+      </Expression>
+      <Expression xsi:type="rx:Defer">
+        <Workflow>
+          <Nodes>
+            <Expression xsi:type="WorkflowInput">
+              <Name>Source1</Name>
+            </Expression>
+            <Expression xsi:type="Multiply">
+              <Operand xsi:type="IntProperty">
+                <Value>2</Value>
+              </Operand>
+            </Expression>
+            <Expression xsi:type="rx:PublishSubject">
+              <Name>Values</Name>
+            </Expression>
+            <Expression xsi:type="Combinator">
+              <Combinator xsi:type="rx:Timer">
+                <rx:DueTime>PT0S</rx:DueTime>
+                <rx:Period>PT0S</rx:Period>
+              </Combinator>
+            </Expression>
+            <Expression xsi:type="rx:SelectMany">
+              <Workflow>
+                <Nodes>
+                  <Expression xsi:type="WorkflowInput">
+                    <Name>Source1</Name>
+                  </Expression>
+                  <Expression xsi:type="SubscribeSubject">
+                    <Name>Values</Name>
+                  </Expression>
+                  <Expression xsi:type="WorkflowOutput" />
+                </Nodes>
+                <Edges>
+                  <Edge From="1" To="2" Label="Source1" />
+                </Edges>
+              </Workflow>
+            </Expression>
+            <Expression xsi:type="WorkflowOutput" />
+          </Nodes>
+          <Edges>
+            <Edge From="0" To="1" Label="Source1" />
+            <Edge From="1" To="2" Label="Source1" />
+            <Edge From="3" To="4" Label="Source1" />
+            <Edge From="4" To="5" Label="Source1" />
+          </Edges>
+        </Workflow>
+      </Expression>
+    </Nodes>
+    <Edges>
+      <Edge From="0" To="1" Label="Source1" />
+      <Edge From="2" To="3" Label="Source1" />
+    </Edges>
+  </Workflow>
+</WorkflowBuilder>
\ No newline at end of file
diff --git a/Bonsai.Editor.Tests/WorkflowEditorDefinitionTests.cs b/Bonsai.Editor.Tests/WorkflowEditorDefinitionTests.cs
new file mode 100644
index 00000000..c99cebfe
--- /dev/null
+++ b/Bonsai.Editor.Tests/WorkflowEditorDefinitionTests.cs
@@ -0,0 +1,22 @@
+using Bonsai.Editor.GraphModel;
+using Bonsai.Reactive;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Bonsai.Editor.Tests
+{
+    public partial class WorkflowEditorTests
+    {
+        [TestMethod]
+        public void GetSubjectDefinition_NestedSubscribeSubject_ReturnsClosestDefinition()
+        {
+            var workflowBuilder = LoadEmbeddedWorkflow("NestedSubscribeSubjectWithClosestRedefinition.bonsai");
+            var deferBuilder = workflowBuilder.Workflow.FindExpressionBuilder<Defer>();
+            Assert.IsNotNull(deferBuilder);
+            var selectManyBuilder = deferBuilder.Workflow.FindExpressionBuilder<SelectMany>();
+            Assert.IsNotNull(selectManyBuilder);
+            var definition = workflowBuilder.GetSubjectDefinition(selectManyBuilder.Workflow, "Values");
+            Assert.IsNotNull(definition);
+            Assert.AreSame(deferBuilder.Workflow, definition.Root.Key);
+        }
+    }
+}
diff --git a/Bonsai.Editor.Tests/WorkflowEditorTests.cs b/Bonsai.Editor.Tests/WorkflowEditorTests.cs
index bf037efd..4b4930d0 100644
--- a/Bonsai.Editor.Tests/WorkflowEditorTests.cs
+++ b/Bonsai.Editor.Tests/WorkflowEditorTests.cs
@@ -1,11 +1,9 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel.Design;
 using System.IO;
 using System.Linq;
 using System.Xml;
 using Bonsai.Dag;
-using Bonsai.Design;
 using Bonsai.Editor.GraphModel;
 using Bonsai.Expressions;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
@@ -13,7 +11,7 @@
 namespace Bonsai.Editor.Tests
 {
     [TestClass]
-    public class WorkflowEditorTests
+    public partial class WorkflowEditorTests
     {
         static Stream LoadEmbeddedResource(string name)
         {
diff --git a/Bonsai.Editor/ExportHelper.cs b/Bonsai.Editor/ExportHelper.cs
index d8be2591..e5b8cf57 100644
--- a/Bonsai.Editor/ExportHelper.cs
+++ b/Bonsai.Editor/ExportHelper.cs
@@ -1,5 +1,4 @@
 using System.Drawing;
-using System.Linq;
 using System.Windows.Forms;
 using Bonsai.Editor.GraphModel;
 using Bonsai.Editor.GraphView;
diff --git a/Bonsai.Editor/GraphModel/WorkflowBuilderExtensions.cs b/Bonsai.Editor/GraphModel/WorkflowBuilderExtensions.cs
index e529feae..b6b8b8f0 100644
--- a/Bonsai.Editor/GraphModel/WorkflowBuilderExtensions.cs
+++ b/Bonsai.Editor/GraphModel/WorkflowBuilderExtensions.cs
@@ -51,7 +51,7 @@ from element in level
                         let subjectBuilder = element.Builder as SubjectExpressionBuilder
                         where subjectBuilder != null && subjectBuilder.Name == name
                         select new SubjectDefinition(level, subjectBuilder, element.IsReadOnly))
-                        .LastOrDefault();
+                        .FirstOrDefault();
             }
 
             return null;
diff --git a/Bonsai/ScriptExtensionsEnvironment.cs b/Bonsai/ScriptExtensionsEnvironment.cs
index f6d54f06..d73e331a 100644
--- a/Bonsai/ScriptExtensionsEnvironment.cs
+++ b/Bonsai/ScriptExtensionsEnvironment.cs
@@ -1,6 +1,5 @@
 using Bonsai.Configuration;
 using Bonsai.Editor;
-using System;
 using System.Collections.Generic;
 using System.Reflection;