diff --git a/xpinstall/wizard/unix/src2/mozilla-installer b/xpinstall/wizard/unix/src2/mozilla-installer
index 5d6edbc3c21..281244f6c8a 100755
--- a/xpinstall/wizard/unix/src2/mozilla-installer
+++ b/xpinstall/wizard/unix/src2/mozilla-installer
@@ -36,11 +36,12 @@
 #=====================================================================
 
 
-LD_LIBRARY_PATH=.:$LD_LIBRARY_PATH
-export LD_LIBRARY_PATH
+LD_LIBRARY_PATH=.${LD_LIBRARY_PATH+":$LD_LIBRARY_PATH"}
+LIBPATH=.${LIBPATH+":$LIBPATH"}
+export LD_LIBRARY_PATH LIBPATH
 unset MOZILLA_FIVE_HOME
 
-PATH=.:$PATH
+PATH=.${PATH+":$PATH"}
 export PATH
 
 BASEDIR=`dirname $0`