diff --git a/build_release_windows.bat b/build_release_windows.bat
index b6b082e..a5de47b 100755
--- a/build_release_windows.bat
+++ b/build_release_windows.bat
@@ -1,5 +1,6 @@
 
 IF NOT DEFINED WORKSPACE SET WORKSPACE=%~dp0
+IF NOT DEFINED IS_NIGHTLY_BUILD SET IS_NIGHTLY_BUILD=1
 
 IF %IS_NIGHTLY_BUILD% EQU 1 (
   SET FGBUILDTYPE=Nightly