diff --git a/src/exchange/test_taler_exchange_httpd.sh b/src/exchange/test_taler_exchange_httpd.sh
index 2b55ef5f4..6e51e06c1 100755
--- a/src/exchange/test_taler_exchange_httpd.sh
+++ b/src/exchange/test_taler_exchange_httpd.sh
@@ -21,8 +21,8 @@
 #
 #
 # Clear environment from variables that override config.
-export XDG_DATA_HOME=
-export XDG_CONFIG_HOME=
+unset XDG_DATA_HOME
+unset XDG_CONFIG_HOME
 #
 # Setup keys.
 taler-exchange-keyup -c test_taler_exchange_httpd.conf