diff --git a/build_tools/prep_tarball b/build_tools/prep_tarball
index 6afb99ee0a283fc6cd40ab3c75d076b2e430ec07..49c36f447385e1d85b198522ef1ee2f15cbe2b64 100755
--- a/build_tools/prep_tarball
+++ b/build_tools/prep_tarball
@@ -8,11 +8,16 @@
 make -C sounds MENUSELECT_CORE_SOUNDS=CORE-SOUNDS-EN-GSM MENUSELECT_MOH=MOH-FREEPLAY-WAV WGET=wget DOWNLOAD=wget all
 make AWK=awk GREP=grep menuselect-tree
 
+make_tex_docs() {
+    # make backup of asterisk.tex because we are going to alter it
+    cp asterisk.tex asterisk.tex.orig
+    sed -e "s/ASTERISKVERSION/${VERSION}/" asterisk.tex > asterisk_local.tex
+    mv asterisk_local.tex asterisk.tex
+    rubber --pdf asterisk.tex
+    latex2html asterisk.tex
+    # restore backup of asterisk.tex
+    mv asterisk.tex.orig asterisk.tex
+}
+
 VERSION=`cat .version`
-# make backup of asterisk.tex because we are going to alter it
-cp asterisk.tex asterisk.tex.orig
-sed -e "s/ASTERISKVERSION/${VERSION}/" doc/tex/asterisk.tex > doc/tex/asterisk_local.tex
-mv asterisk_local.tex asterisk.tex
-cd doc/tex && rubber --pdf asterisk.tex && latex2html asterisk.tex
-# restore backup of asterisk.tex
-mv asterisk.tex.orig asterisk.tex
+cd doc/tex && make_tex_docs