diff --git a/csharp/ql/lib/semmle/code/asp/WebConfig.qll b/csharp/ql/lib/semmle/code/asp/WebConfig.qll
index 34fa9cf3972..49e42fce5c1 100644
--- a/csharp/ql/lib/semmle/code/asp/WebConfig.qll
+++ b/csharp/ql/lib/semmle/code/asp/WebConfig.qll
@@ -11,6 +11,13 @@ class WebConfigXml extends XmlFile {
   WebConfigXml() { this.getName().matches("%Web.config") }
 }
 
+/**
+ * A `Web.config` transformation file.
+ */
+class WebConfigReleaseTransformXml extends XmlFile {
+  WebConfigReleaseTransformXml() { this.getName().matches("%Web.Release.config") }
+}
+
 /** DEPRECATED: Alias for WebConfigXml */
 deprecated class WebConfigXML = WebConfigXml;
 
@@ -19,6 +26,11 @@ class ConfigurationXmlElement extends XmlElement {
   ConfigurationXmlElement() { this.getName().toLowerCase() = "configuration" }
 }
 
+/** A `<compilation>` tag in an ASP.NET configuration file. */
+class CompilationXmlElement extends XmlElement {
+  CompilationXmlElement() { this.getName().toLowerCase() = "compilation" }
+}
+
 /** DEPRECATED: Alias for ConfigurationXmlElement */
 deprecated class ConfigurationXMLElement = ConfigurationXmlElement;
 
@@ -149,3 +161,15 @@ class HttpCookiesElement extends XmlElement {
   /** DEPRECATED: Alias for isRequireSsl */
   deprecated predicate isRequireSSL() { this.isRequireSsl() }
 }
+
+/** A `Transform` attribute in a Web.config transformation file. */
+class TransformXmlAttribute extends XmlAttribute {
+  TransformXmlAttribute() { this.getName().toLowerCase() = "transform" }
+
+  /**
+   * Gets the list of attribute removals in `Transform=RemoveAttributes(list)`.
+   */
+  string getRemoveAttributes() {
+    result = this.getValue().regexpCapture("RemoveAttributes\\((.*)\\)", 1).splitAt(",")
+  }
+}
diff --git a/csharp/ql/src/Security Features/CWE-011/ASPNetDebug.ql b/csharp/ql/src/Security Features/CWE-011/ASPNetDebug.ql
index 1180d4990f8..308f3eeeac2 100644
--- a/csharp/ql/src/Security Features/CWE-011/ASPNetDebug.ql	
+++ b/csharp/ql/src/Security Features/CWE-011/ASPNetDebug.ql	
@@ -19,6 +19,17 @@ import semmle.code.asp.WebConfig
 
 from SystemWebXmlElement web, XmlAttribute debugAttribute
 where
-  debugAttribute = web.getAChild("compilation").getAttribute("debug") and
-  not debugAttribute.getValue().toLowerCase() = "false"
+  exists(CompilationXmlElement compilation | compilation.getParent() = web |
+    debugAttribute = compilation.getAttribute("debug") and
+    not debugAttribute.getValue().toLowerCase() = "false"
+  ) and
+  not exists(
+    TransformXmlAttribute attribute, CompilationXmlElement compilation,
+    WebConfigReleaseTransformXml file
+  |
+    compilation = attribute.getElement() and
+    file = compilation.getFile() and
+    attribute.getRemoveAttributes() = "debug" and
+    file.getParentContainer() = web.getFile().getParentContainer()
+  )
 select debugAttribute, "The 'debug' flag is set for an ASP.NET configuration file."