diff --git a/mail/configure.in b/mail/configure.in
index 415ef54dba..153bcb1e35 100644
--- a/mail/configure.in
+++ b/mail/configure.in
@@ -8,7 +8,6 @@ dnl Things we need to carry from confvars.sh
 AC_DEFINE(MOZ_THUNDERBIRD)
 AC_SUBST(MOZ_THUNDERBIRD)
 AC_SUBST(THUNDERBIRD_VERSION)
-AC_DEFINE(MOZ_SEPARATE_MANIFEST_FOR_THEME_OVERRIDES)
 AC_SUBST(MOZ_BUNDLED_FONTS)
 
 dnl More things we need to carry from confvars.sh
diff --git a/mail/moz.configure b/mail/moz.configure
index 97ede28078..24358d1740 100644
--- a/mail/moz.configure
+++ b/mail/moz.configure
@@ -4,6 +4,8 @@
 # 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/.
 
+set_define('MOZ_SEPARATE_MANIFEST_FOR_THEME_OVERRIDES', True)
+
 imply_option('MOZ_PLACES', True)
 imply_option('MOZ_ALLOW_LEGACY_EXTENSIONS', True)
 
diff --git a/suite/configure.in b/suite/configure.in
index 74f2cec055..ebeb984765 100644
--- a/suite/configure.in
+++ b/suite/configure.in
@@ -8,7 +8,6 @@ dnl Things we need to carry from confvars.sh
 AC_DEFINE(MOZ_SUITE)
 AC_SUBST(MOZ_SUITE)
 AC_SUBST(SEAMONKEY_VERSION)
-AC_DEFINE(MOZ_SEPARATE_MANIFEST_FOR_THEME_OVERRIDES)
 AC_SUBST(MOZ_BUNDLED_FONTS)
 AC_SUBST(MOZ_IRC)
 AC_SUBST(MOZ_DOMINSPECTOR)
diff --git a/suite/confvars.sh b/suite/confvars.sh
index da0df0b7b0..c665c7ba4f 100755
--- a/suite/confvars.sh
+++ b/suite/confvars.sh
@@ -27,7 +27,6 @@ SEAMONKEY_VERSION=$MOZ_APP_VERSION
 
 MOZ_APP_ID={92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}
 MOZ_PROFILE_MIGRATOR=1
-MOZ_SEPARATE_MANIFEST_FOR_THEME_OVERRIDES=1
 
 if test "$NIGHTLY_BUILD"; then
   MOZ_RUST_URLPARSE=1
diff --git a/suite/moz.configure b/suite/moz.configure
index 60081e1383..005579be12 100644
--- a/suite/moz.configure
+++ b/suite/moz.configure
@@ -4,6 +4,8 @@
 # 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/.
 
+set_define('MOZ_SEPARATE_MANIFEST_FOR_THEME_OVERRIDES', True)
+
 imply_option('MOZ_PLACES', True)
 imply_option('MOZ_SERVICES_SYNC', True)
 imply_option('MOZ_ALLOW_LEGACY_EXTENSIONS', True)