diff --git a/ql/src/codeql_ruby/controlflow/ControlFlowGraph.qll b/ql/src/codeql_ruby/controlflow/ControlFlowGraph.qll
index 080f64da579..75674fb10e5 100644
--- a/ql/src/codeql_ruby/controlflow/ControlFlowGraph.qll
+++ b/ql/src/codeql_ruby/controlflow/ControlFlowGraph.qll
@@ -7,14 +7,34 @@ private import internal.ControlFlowGraphImpl
 private import internal.Splitting
 private import internal.Completion
 
-private class CfgScopeRange = @method or @block or @do_block;
+private class CfgScopeRange =
+  @program or @begin_block or @end_block or @module or @class or @singleton_class or @method or
+      @singleton_method or @block or @do_block;
 
 /** An AST node with an associated control-flow graph. */
 class CfgScope extends AstNode, CfgScopeRange {
   /** Gets the name of this scope. */
   string getName() {
+    this instanceof Program and
+    result = "top-level"
+    or
+    this instanceof BeginBlock and
+    result = "BEGIN block"
+    or
+    this instanceof EndBlock and
+    result = "END block"
+    or
+    result = this.(Module).getName().toString()
+    or
+    result = this.(Class).getName().toString()
+    or
+    this instanceof SingletonClass and
+    result = "singleton class"
+    or
     result = this.(Method).getName().toString()
     or
+    result = this.(SingletonMethod).getName().toString()
+    or
     this instanceof Block and
     result = "block"
     or
diff --git a/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll b/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll
index 283f77d4908..1fd3ac8ec72 100644
--- a/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll
+++ b/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll
@@ -141,7 +141,14 @@ abstract private class StandardNode extends ControlFlowTree {
   abstract AstNode getChildNode(int i);
 
   private AstNode getChildNodeRanked(int i) {
-    result = rank[i + 1](AstNode child, int j | child = this.getChildNode(j) | child order by j)
+    result =
+      rank[i + 1](AstNode child, int j |
+        child = this.getChildNode(j) and
+        // Never descend into children with a separate scope
+        not child instanceof CfgScope
+      |
+        child order by j
+      )
   }
 
   /** Gets the first child node of this element. */
@@ -150,24 +157,17 @@ abstract private class StandardNode extends ControlFlowTree {
   /** Gets the last child node of this node. */
   final AstNode getLastChildNode() {
     exists(int last |
-      last = max(int i | exists(this.getChildNodeRanked(i))) and
-      result = this.getChildNodeRanked(last)
+      result = this.getChildNodeRanked(last) and
+      not exists(this.getChildNodeRanked(last + 1))
     )
   }
 
-  /** Gets the `i`th child, which is not the last node. */
-  pragma[nomagic]
-  private AstNode getNonLastChildNode(int i) {
-    result = this.getChildNodeRanked(i) and
-    not result = this.getLastChildNode()
-  }
-
-  final override predicate propagatesAbnormal(AstNode child) { child = this.getChildNode(_) }
+  final override predicate propagatesAbnormal(AstNode child) { child = this.getChildNodeRanked(_) }
 
   pragma[nomagic]
   override predicate succ(AstNode pred, AstNode succ, Completion c) {
     exists(int i |
-      last(this.getNonLastChildNode(i), pred, c) and
+      last(this.getChildNodeRanked(i), pred, c) and
       c instanceof NormalCompletion and
       first(this.getChildNodeRanked(i + 1), succ)
     )
@@ -246,6 +246,10 @@ private module Trees {
     }
   }
 
+  private class BeginBlockTree extends StandardPreOrderTree, BeginBlock {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+  }
+
   private class BinaryTree extends StandardPostOrderTree, Binary {
     BinaryTree() { not this instanceof LogicalAndAstNode and not this instanceof LogicalOrAstNode }
 
@@ -272,6 +276,12 @@ private module Trees {
     }
   }
 
+  private class ClassTree extends StandardPreOrderTree, Class {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+
+    override predicate isHidden() { any() }
+  }
+
   private class DoTree extends StandardPreOrderTree, Do {
     final override AstNode getChildNode(int i) { result = this.getChild(i) }
 
@@ -290,6 +300,10 @@ private module Trees {
     override predicate isHidden() { any() }
   }
 
+  private class EndBlockTree extends StandardPreOrderTree, EndBlock {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+  }
+
   private class IdentifierTree extends LeafTree, Identifier { }
 
   private class IfElsifTree extends PreOrderTree, IfElsifAstNode {
@@ -392,6 +406,12 @@ private module Trees {
     }
   }
 
+  private class ModuleTree extends StandardPreOrderTree, Module {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+
+    override predicate isHidden() { any() }
+  }
+
   private class NextTree extends StandardPostOrderTree, Next {
     final override AstNode getChildNode(int i) { result = this.getChild() and i = 0 }
   }
@@ -408,6 +428,12 @@ private module Trees {
     final override AstNode getChildNode(int i) { result = this.getChild(i) }
   }
 
+  private class ProgramTree extends StandardPreOrderTree, Program {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+
+    override predicate isHidden() { any() }
+  }
+
   private class RedoTree extends StandardPostOrderTree, Redo {
     final override AstNode getChildNode(int i) { result = this.getChild() and i = 0 }
   }
@@ -416,6 +442,18 @@ private module Trees {
     final override AstNode getChildNode(int i) { result = this.getChild() and i = 0 }
   }
 
+  private class SingletonClassTree extends StandardPreOrderTree, SingletonClass {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+
+    override predicate isHidden() { any() }
+  }
+
+  private class SingletonMethodTree extends StandardPreOrderTree, SingletonMethod {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+
+    override predicate isHidden() { any() }
+  }
+
   private class StringTree extends LeafTree, String { }
 
   private class ThenTree extends StandardPreOrderTree, Then {