diff --git a/config/moz.build b/config/moz.build
index d9c28fe54d05..ce6297393373 100644
--- a/config/moz.build
+++ b/config/moz.build
@@ -47,6 +47,10 @@ if CONFIG['WRAP_STL_INCLUDES']:
         stl_compiler = 'msvc'
 
     if stl_compiler:
+        # Note that the 'stl_wrappers' folder is known to the build system as
+        # containing generated files; if this is changed here then the code in
+        # GeneratedFile.__init__ in python/mozbuild/mozbuild/frontend/data.py
+        # might need to be updated accordingly as well.
         template_file = SRCDIR + '/%s-stl-wrapper.template.h' % stl_compiler
         output_dir = '../dist/stl_wrappers'
         # We have to use a sentinel file as the first file because the
diff --git a/python/mozbuild/mozbuild/frontend/data.py b/python/mozbuild/mozbuild/frontend/data.py
index 65d7dfd3cff2..f993a5cef79f 100644
--- a/python/mozbuild/mozbuild/frontend/data.py
+++ b/python/mozbuild/mozbuild/frontend/data.py
@@ -1170,9 +1170,8 @@ class GeneratedFile(ContextDerived):
             '.inc',
             '.py',
             '.rs',
-            'new', # 'new' is an output from make-stl-wrappers.py
         )
-        self.required_for_compile = [f for f in self.outputs if f.endswith(suffixes)]
+        self.required_for_compile = [f for f in self.outputs if f.endswith(suffixes) or 'stl_wrappers/' in f]
 
 
 class ChromeManifestEntry(ContextDerived):