diff --git a/tests/test-extdiff b/tests/test-extdiff
--- a/tests/test-extdiff
+++ b/tests/test-extdiff
@@ -1,8 +1,7 @@
 #!/bin/sh
 
-HGRCPATH=$HGTMP/.hgrc; export HGRCPATH
-echo "[extensions]" >> $HGTMP/.hgrc
-echo "extdiff=" >> $HGTMP/.hgrc
+echo "[extensions]" >> $HGRCPATH
+echo "extdiff=" >> $HGRCPATH
 
 hg init a
 cd a
@@ -14,9 +13,9 @@ if [ $? -ne 0 ]; then
 fi
 hg extdiff -o -Nr $opt
 
-echo "[extdiff]" >> $HGTMP/.hgrc
-echo "cmd.falabala=echo" >> $HGTMP/.hgrc
-echo "opts.falabala=diffing" >> $HGTMP/.hgrc
+echo "[extdiff]" >> $HGRCPATH
+echo "cmd.falabala=echo" >> $HGRCPATH
+echo "opts.falabala=diffing" >> $HGRCPATH
 
 hg falabala