diff --git a/malepoon/configure.in b/malepoon/configure.in
index 1c1b75081..e60bebc6b 100644
--- a/malepoon/configure.in
+++ b/malepoon/configure.in
@@ -7,6 +7,8 @@ dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
 dnl Things we need to carry from confvars.sh
 AC_DEFINE(MOZ_PHOENIX)
 AC_SUBST(MOZ_PHOENIX)
+AC_DEFINE(MOZ_PHOENIX_EXTENSIONS)
+AC_SUBST(MOZ_PHOENIX_EXTENSIONS)
 AC_DEFINE(MC_PALEMOON)
 AC_SUBST(MC_PALEMOON)
 
diff --git a/malepoon/confvars.sh b/malepoon/confvars.sh
index ede36c5fa..ae6bcec85 100644
--- a/malepoon/confvars.sh
+++ b/malepoon/confvars.sh
@@ -42,6 +42,7 @@ MC_PALEMOON=1
 # Enables conditional code in the platform for historically
 # Firefox-like browsers
 MOZ_PHOENIX=1
+MOZ_PHOENIX_EXTENSIONS=1
 
 # Lightweight Themes
 MOZ_PERSONAS=1