diff --git a/calendar/lightning/Makefile.in b/calendar/lightning/Makefile.in
index 84705489d0..a917384ac2 100644
--- a/calendar/lightning/Makefile.in
+++ b/calendar/lightning/Makefile.in
@@ -58,7 +58,7 @@ PREF_JS_EXPORTS = $(srcdir)/content/lightning.js
 
 # Lighting version number
 LIGHTNING_VERSION := $(shell cat $(srcdir)/../sunbird/config/version.txt)
-if defined(MOZILLA_5_0_BRANCH)
+ifdef MOZILLA_5_0_BRANCH
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-50.txt)
 SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-50.txt)
 else
diff --git a/calendar/providers/gdata/Makefile.in b/calendar/providers/gdata/Makefile.in
index 19aa6a3a1b..4b59304a32 100644
--- a/calendar/providers/gdata/Makefile.in
+++ b/calendar/providers/gdata/Makefile.in
@@ -50,7 +50,7 @@ XPI_PKGNAME = gdata-provider
 STRIP_XPI = 1
 
 CALENDAR_VERSION := $(shell cat $(topsrcdir)/calendar/sunbird/config/version.txt)
-if defined(MOZILLA_5_0_BRANCH)
+ifdef MOZILLA_5_0_BRANCH
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-50.txt)
 SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-50.txt)
 else
diff --git a/calendar/timezones/Makefile.in b/calendar/timezones/Makefile.in
index a759a04fe1..a3693832fc 100644
--- a/calendar/timezones/Makefile.in
+++ b/calendar/timezones/Makefile.in
@@ -77,7 +77,7 @@ INSTALL_EXTENSION_ID = calendar-timezones@mozilla.org
 endif
 
 CALENDAR_VERSION := $(shell cat $(topsrcdir)/calendar/sunbird/config/version.txt)
-if defined(MOZILLA_5_0_BRANCH)
+ifdef MOZILLA_5_0_BRANCH
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version-50.txt)
 SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version-50.txt)
 else