diff --git a/build_release_windows.bat b/build_release_windows.bat
index 52fc061..8c6e264 100755
--- a/build_release_windows.bat
+++ b/build_release_windows.bat
@@ -105,8 +105,8 @@ GOTO End
 
 :writeBaseConfig
 ECHO #define FGHarnessPath "x:" > InstallConfig.iss
-ECHO #define FGVersion "%FLIGHTGEAR_VERSION%" > InstallConfig.iss
-ECHO #define FGVersionGroup "%FLIGHTGEAR_VERSION_MAJOR%.%FLIGHTGEAR_VERSION_MINOR%" > InstallConfig.iss
+ECHO #define FGVersion "%FLIGHTGEAR_VERSION%" >> InstallConfig.iss
+ECHO #define FGVersionGroup "%FLIGHTGEAR_VERSION_MAJOR%.%FLIGHTGEAR_VERSION_MINOR%" >> InstallConfig.iss
 ECHO #define OSGVersion "%OSG_VERSION%" >> InstallConfig.iss
 ECHO #define OSGSoNumber "%OSG_SO_NUMBER%" >> InstallConfig.iss
 ECHO #define OTSoNumber "%OT_SO_NUMBER%" >> InstallConfig.iss