diff --git a/services/sync/Makefile.in b/services/sync/Makefile.in
deleted file mode 100644
index 7b2853b5831d..000000000000
--- a/services/sync/Makefile.in
+++ /dev/null
@@ -1,16 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-# Definitions used by constants.js.
-weave_version := 1.45.0
-weave_id      := {340c2bbc-ce74-4362-90b5-7c26312808ef}
-
-# Preprocess files.
-SYNC_PP := modules/constants.js
-SYNC_PP_FLAGS := \
- -Dweave_version=$(weave_version) \
- -Dweave_id='$(weave_id)'
-SYNC_PP_PATH = $(FINAL_TARGET)/modules/services-sync
-PP_TARGETS += SYNC_PP
-
diff --git a/services/sync/moz.build b/services/sync/moz.build
index 3bead3c32259..7abfbc4a63c1 100644
--- a/services/sync/moz.build
+++ b/services/sync/moz.build
@@ -41,6 +41,14 @@ EXTRA_JS_MODULES['services-sync'] += [
     'modules/util.js',
 ]
 
+EXTRA_PP_JS_MODULES['services-sync'] += [
+    'modules/constants.js',
+]
+
+# Definitions used by constants.js
+DEFINES['weave_version'] = '1.45.0'
+DEFINES['weave_id'] = '{340c2bbc-ce74-4362-90b5-7c26312808ef}'
+
 EXTRA_JS_MODULES['services-sync'].engines += [
     'modules/engines/addons.js',
     'modules/engines/bookmarks.js',