diff --git a/cpp/ql/src/semmle/code/cpp/File.qll b/cpp/ql/src/semmle/code/cpp/File.qll
index 28f53cbf6033..221093977046 100644
--- a/cpp/ql/src/semmle/code/cpp/File.qll
+++ b/cpp/ql/src/semmle/code/cpp/File.qll
@@ -309,6 +309,12 @@ class File extends Container, @file {
     ) or exists(File parent |
       parent.compiledAsMicrosoft() and
       parent.getAnIncludedFile() = this
+    ) or (
+      getAbsolutePath().charAt(1) = ":"
+      	// this is not ideal, it detects compilation on a Windows file system
+      	// as a heuristic approximation to compilation with a Microsoft compiler.
+    ) or (
+      getAbsolutePath().charAt(1) = "/"
     )
   }