diff --git a/build_tools/prep_tarball b/build_tools/prep_tarball
index 4d4aa41b82..b5b64a24ee 100755
--- a/build_tools/prep_tarball
+++ b/build_tools/prep_tarball
@@ -7,6 +7,4 @@
 
 make -C sounds all MENUSELECT_CORE_SOUNDS=CORE-SOUNDS-EN-GSM MENUSELECT_MOH=MOH-FREEPLAY-WAV WGET=wget DOWNLOAD=wget
 
-cd doc
-rubber asterisk.tex 
-cd ..
+cd doc && rubber --pdf asterisk.tex