diff --git a/stack/erp5/buildout.hash.cfg b/stack/erp5/buildout.hash.cfg
index eca9087db5344215f5693c8750ecceb0dc7e393a..6472e4e365c7418087310d3302ee21c3a625e9a1 100644
--- a/stack/erp5/buildout.hash.cfg
+++ b/stack/erp5/buildout.hash.cfg
@@ -90,7 +90,7 @@ md5sum = 0ac4b74436f554cd677f19275d18d880
 
 [template-zope]
 filename = instance-zope.cfg.in
-md5sum = 9547bacad0635b0f64cac48f15c4e9ae
+md5sum = 9c580be982d8c63ec06fc273ef3cb971
 
 [template-balancer]
 filename = instance-balancer.cfg.in
diff --git a/stack/erp5/instance-zope.cfg.in b/stack/erp5/instance-zope.cfg.in
index 63641842eeec9f686bb5f631e30da6d51b204ae0..0d09a24a2d1f7dbec9c4c879c43634a387e2d110 100644
--- a/stack/erp5/instance-zope.cfg.in
+++ b/stack/erp5/instance-zope.cfg.in
@@ -87,7 +87,7 @@ environment +=
   JUPYTER_PATH=${directory:jupyter-dir}
   JUPYTER_CONFIG_DIR=${directory:jupyter-config-dir}
   JUPYTER_RUNTIME_DIR=${directory:jupyter-runtime-dir}
-{% if slapparameter_dict.get('python-hash-seed') %}
+{% if slapparameter_dict.get('python-hash-seed') != '' %}
   PYTHONHASHSEED={{ slapparameter_dict['python-hash-seed'] }}
 {% endif %}
 {% if slapparameter_dict.get('wendelin-core-zblk-fmt') %}
@@ -476,7 +476,7 @@ wrapper-path = ${buildout:bin-directory}/runUnitTest
 recipe = slapos.recipe.template
 inline =
   #!/bin/sh
-  {% if slapparameter_dict.get('python-hash-seed') %}
+  {% if slapparameter_dict.get('python-hash-seed') != '' %}
   PYTHONHASHSEED={{ slapparameter_dict['python-hash-seed'] }}
   {% endif %}
   if [ -z "$PYTHONHASHSEED" ]; then