diff --git a/bin/prepare_minion.py b/bin/prepare_minion.py
index a1f15bd..92d45c5 100755
--- a/bin/prepare_minion.py
+++ b/bin/prepare_minion.py
@@ -5,13 +5,17 @@ import roles
 import os
 import yaml
 import socket
+import yaml
 
 roles = roles.get()
 grainsfile = '/etc/salt/grains'
-idfile = 'pillar/id/' + socket.gethostname() + '.sls'
+idfile = os.path.join('pillar/id/', socket.gethostname() + '.sls')
 configfile = '/etc/salt/minion.d/local.conf'
 mypwd = os.getcwd()
+formulasfile = 'formulas.yaml'
+formulasdir = '/srv/formulas'
 
+configdata = {'file_roots': {'production': ['/srv/salt']}}
 grainsdata = {'roles': roles}
 
 with open(grainsfile, mode='w') as grainsfh:
@@ -20,16 +24,16 @@ with open(grainsfile, mode='w') as grainsfh:
 with open(idfile, mode='w') as idfh:
 	idfh.write('# empty')
 
-# to-do: include formulas automatically, maybe from some YAML file?
+with open(formulasfile, mode='r') as formulasfh:
+    formulas = yaml.load(formulasfh, Loader=yaml.FullLoader)
+
+for formula in formulas:
+    formula = os.path.join('/srv/formulas/', formula + '-formula')
+    configdata['file_roots']['production'].append(formula)
+
 with open(configfile, mode='w') as configfh:
-    configfh.write('''# written by prepare_minion.py
-file_roots:
-  production:
-    - /srv/salt
-    - /srv/formulas/salt-formula
-    - /srv/formulas/users-formula
-    - /srv/formulas/postfix-formula
-''')
+    configfh.write('# written by prepare_minion.py\n')
+    yaml.dump(configdata, configfh)
 
 os.symlink(mypwd + '/salt', '/srv/salt')
 os.symlink(mypwd + '/pillar', '/srv/pillar')
diff --git a/formulas.yaml b/formulas.yaml
new file mode 120000
index 0000000..46a0cb0
--- /dev/null
+++ b/formulas.yaml
@@ -0,0 +1 @@
+pillar/formulas.yaml
\ No newline at end of file
diff --git a/pillar/formulas.yaml b/pillar/formulas.yaml
new file mode 100644
index 0000000..a9095f1
--- /dev/null
+++ b/pillar/formulas.yaml
@@ -0,0 +1,3 @@
+- postfix
+- salt
+- users
diff --git a/pillar/role/salt/master.sls b/pillar/role/salt/master.sls
index 49785ac..e66774f 100644
--- a/pillar/role/salt/master.sls
+++ b/pillar/role/salt/master.sls
@@ -1,4 +1,4 @@
-{%- set formulas = ['salt', 'users', 'postfix'] -%}
+{%- import_yaml 'formulas.yaml' as formulas -%}
 
 include:
   - role.salt.common