diff --git a/config/rules.mk b/config/rules.mk
index 0097226f938..701f66f8cbb 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -1170,14 +1170,6 @@ endif #} XPT_NAME
 
 ################################################################################
 # Copy each element of EXTRA_COMPONENTS to $(FINAL_TARGET)/components
-ifneq (,$(filter %.js,$(EXTRA_COMPONENTS) $(EXTRA_PP_COMPONENTS)))
-ifeq (,$(filter %.manifest,$(EXTRA_COMPONENTS) $(EXTRA_PP_COMPONENTS)))
-ifndef NO_JS_MANIFEST
-$(error .js component without matching .manifest. See https://developer.mozilla.org/en/XPCOM/XPCOM_changes_in_Gecko_2.0)
-endif
-endif
-endif
-
 ifdef EXTRA_COMPONENTS
 misc:: $(EXTRA_COMPONENTS)
 ifndef NO_DIST_INSTALL
diff --git a/python/mozbuild/mozbuild/frontend/emitter.py b/python/mozbuild/mozbuild/frontend/emitter.py
index 7089eebff05..ad2955f468f 100644
--- a/python/mozbuild/mozbuild/frontend/emitter.py
+++ b/python/mozbuild/mozbuild/frontend/emitter.py
@@ -526,6 +526,17 @@ class TreeMetadataEmitter(LoggingMixin):
         for obj in self._process_xpidl(context):
             yield obj
 
+        # Check for manifest declarations in EXTRA_{PP_,}COMPONENTS.
+        extras = context.get('EXTRA_COMPONENTS', []) + context.get('EXTRA_PP_COMPONENTS', [])
+        if any(e.endswith('.js') for e in extras) and \
+                not any(e.endswith('.manifest') for e in extras) and \
+                not context.get('NO_JS_MANIFEST', False):
+            raise SandboxValidationError('A .js component was specified in EXTRA_COMPONENTS '
+                                         'or EXTRA_PP_COMPONENTS without a matching '
+                                         '.manifest file.  See '
+                                         'https://developer.mozilla.org/en/XPCOM/XPCOM_changes_in_Gecko_2.0 .',
+                                         context);
+            
         # Proxy some variables as-is until we have richer classes to represent
         # them. We should aim to keep this set small because it violates the
         # desired abstraction of the build definition away from makefiles.
diff --git a/python/mozbuild/mozbuild/test/backend/data/variable_passthru/moz.build b/python/mozbuild/mozbuild/test/backend/data/variable_passthru/moz.build
index f4f5bf23430..07e51432d80 100644
--- a/python/mozbuild/mozbuild/test/backend/data/variable_passthru/moz.build
+++ b/python/mozbuild/mozbuild/test/backend/data/variable_passthru/moz.build
@@ -2,7 +2,7 @@
 # Any copyright is dedicated to the Public Domain.
 # http://creativecommons.org/publicdomain/zero/1.0/
 
-EXTRA_COMPONENTS = ['bar.js', 'foo.js']
+EXTRA_COMPONENTS = ['bar.js', 'dummy.manifest', 'foo.js']
 EXTRA_PP_COMPONENTS = ['bar.pp.js', 'foo.pp.js']
 
 FAIL_ON_WARNINGS = True
diff --git a/python/mozbuild/mozbuild/test/backend/test_recursivemake.py b/python/mozbuild/mozbuild/test/backend/test_recursivemake.py
index cfebc8af0ad..584d8a0128b 100644
--- a/python/mozbuild/mozbuild/test/backend/test_recursivemake.py
+++ b/python/mozbuild/mozbuild/test/backend/test_recursivemake.py
@@ -265,6 +265,7 @@ class TestRecursiveMakeBackend(BackendTester):
             ],
             'EXTRA_COMPONENTS': [
                 'EXTRA_COMPONENTS += bar.js',
+                'EXTRA_COMPONENTS += dummy.manifest',
                 'EXTRA_COMPONENTS += foo.js',
             ],
             'EXTRA_PP_COMPONENTS': [
diff --git a/python/mozbuild/mozbuild/test/frontend/data/variable-passthru/moz.build b/python/mozbuild/mozbuild/test/frontend/data/variable-passthru/moz.build
index b88099196d4..08adfa63660 100644
--- a/python/mozbuild/mozbuild/test/frontend/data/variable-passthru/moz.build
+++ b/python/mozbuild/mozbuild/test/frontend/data/variable-passthru/moz.build
@@ -2,7 +2,7 @@
 # Any copyright is dedicated to the Public Domain.
 # http://creativecommons.org/publicdomain/zero/1.0/
 
-EXTRA_COMPONENTS=['fans.js', 'tans.js']
+EXTRA_COMPONENTS = ['dummy.manifest', 'fans.js', 'tans.js']
 EXTRA_PP_COMPONENTS=['fans.pp.js', 'tans.pp.js']
 
 FAIL_ON_WARNINGS = True
diff --git a/python/mozbuild/mozbuild/test/frontend/test_emitter.py b/python/mozbuild/mozbuild/test/frontend/test_emitter.py
index 825d11abf93..da70952674e 100644
--- a/python/mozbuild/mozbuild/test/frontend/test_emitter.py
+++ b/python/mozbuild/mozbuild/test/frontend/test_emitter.py
@@ -160,7 +160,7 @@ class TestEmitterBasic(unittest.TestCase):
 
         wanted = {
             'DISABLE_STL_WRAPPING': True,
-            'EXTRA_COMPONENTS': ['fans.js', 'tans.js'],
+            'EXTRA_COMPONENTS': ['dummy.manifest', 'fans.js', 'tans.js'],
             'EXTRA_PP_COMPONENTS': ['fans.pp.js', 'tans.pp.js'],
             'FAIL_ON_WARNINGS': True,
             'MSVC_ENABLE_PGO': True,