diff --git a/filter_plugins/safe_join.py b/filter_plugins/safe_join.py
new file mode 100644
index 00000000..086d9ae0
--- /dev/null
+++ b/filter_plugins/safe_join.py
@@ -0,0 +1,29 @@
+# file: filter_plugins/safe_join.py
+"""
+Ansible filter plugin that joins a base string and a tail path safely.
+If the base is falsy (None, empty, etc.), returns an empty string.
+"""
+
+def safe_join(base, tail):
+    """
+    Safely join base and tail into a path or URL.
+
+    - base: the base string. If falsy, returns ''.
+    - tail: the string to append. Leading/trailing slashes are handled.
+    - On any exception, returns ''.
+    """
+    try:
+        if not base:
+            return ''
+        base_str = str(base).rstrip('/')
+        tail_str = str(tail).lstrip('/')
+        return f"{base_str}/{tail_str}"
+    except Exception:
+        return ''
+
+
+class FilterModule(object):
+    def filters(self):
+        return {
+            'safe_join': safe_join,
+        }
diff --git a/group_vars/all/15_about.yml b/group_vars/all/15_about.yml
index aa0b86de..b6cfd71a 100644
--- a/group_vars/all/15_about.yml
+++ b/group_vars/all/15_about.yml
@@ -9,18 +9,12 @@ defaults_service_provider:
       city:         "Cybertown"
       postal_code:  "00001"
       country:      "Nexusland"
-    logo: >-
-      {{ (applications.assets_server.url  | safe_var ~ '/logo.png')
-        if applications.assets_server.url  | safe_var else '' }}
+    logo:           "{{ applications.assets_server.url | safe_var | safe_join('logo.png') }}"
   platform:    
     titel:          "CyMaIS Demo"
     subtitel:       "The Future of Self-Hosted Infrastructure. Secure. Automated. Sovereign."
-    logo: >-
-      {{ (applications.assets_server.url  | safe_var ~ '/logo.png')
-        if applications.assets_server.url  | safe_var else '' }}
-    favicon: >-
-      {{ (applications.assets_server.url  | safe_var ~ '/favicon.ico')
-        if applications.assets_server.url  | safe_var else '' }}
+    logo:           "{{ applications.assets_server.url | safe_var | safe_join('logo.png') }}"
+    favicon:        "{{ applications.assets_server.url | safe_var | safe_join('favicon.ico') }}"
   contact:
     bluesky: >-
       {{ ('@' ~ users.administrator.username ~ '.' ~ domains[application_id]['api'])
@@ -36,4 +30,10 @@ defaults_service_provider:
   legal:
     editorial_responsible:  "Johannes Gutenberg"
     source_code:            "https://github.com/kevinveenbirkenbach/cymais"
-    imprint:                "{{ web_protocol }}://{{domains.html_server}}/imprint.html"
\ No newline at end of file
+    imprint: >-
+      {{ "{protocol}://{domain}/imprint.html"
+        | safe_placeholders({
+            'protocol': web_protocol,
+            'domain':   domains.html_server
+          })
+      }}
diff --git a/roles/docker-discourse/templates/discourse_application.yml.j2 b/roles/docker-discourse/templates/discourse_application.yml.j2
index 2642c3c9..0b3a5083 100644
--- a/roles/docker-discourse/templates/discourse_application.yml.j2
+++ b/roles/docker-discourse/templates/discourse_application.yml.j2
@@ -51,8 +51,10 @@ env:
   DISCOURSE_DEVELOPER_EMAILS:       {{users.administrator.email}}
 
   # Set Logo
+  {% if service_provider.platform.logo | bool %}
   DISCOURSE_LOGO_URL:       "{{ service_provider.platform.logo  }}"
   DISCOURSE_LOGO_SMALL_URL: "{{ service_provider.platform.logo  }}"
+  {% endif %}
 
   # SMTP ADDRESS, username, and password are required
   # WARNING the char '#' in SMTP password can cause problems!
diff --git a/roles/docker-listmonk/vars/main.yml b/roles/docker-listmonk/vars/main.yml
index 3aec8df7..c9595607 100644
--- a/roles/docker-listmonk/vars/main.yml
+++ b/roles/docker-listmonk/vars/main.yml
@@ -65,8 +65,9 @@ listmonk_settings:
 #  - key: "messengers"
 #    value: '[]'
 
-  - key: "app.logo_url"
-    value: '"{{ service_provider.platform.logo }}"'
+  - key:    "app.logo_url"
+    value:  '"{{ service_provider.platform.logo }}"'
+    when:   service_provider.platform.logo | bool
 
   - key: "app.site_name"
     value: '"{{ service_provider.company.titel }} Mailing list"'
@@ -115,8 +116,9 @@ listmonk_settings:
 #  - key: "app.concurrency"
 #    value: '10'
 
-  - key: "app.favicon_url"
-    value: '"{{ service_provider.platform.favicon }}"'
+  - key:    "app.favicon_url"
+    value:  '"{{ service_provider.platform.favicon }}"'
+    when:   service_provider.platform.favicon | bool
 
 #  - key: "bounce.postmark"
 #    value: '{"enabled": false, "password": "", "username": ""}'
diff --git a/tests/unit/test_safe_join.py b/tests/unit/test_safe_join.py
new file mode 100644
index 00000000..1d3fd75f
--- /dev/null
+++ b/tests/unit/test_safe_join.py
@@ -0,0 +1,51 @@
+import unittest
+import sys
+import os
+
+# Ensure filter_plugins directory is on the path
+sys.path.insert(
+    0,
+    os.path.abspath(os.path.join(os.path.dirname(__file__), '../../filter_plugins'))
+)
+
+from safe_join import safe_join
+
+class TestSafeJoinFilter(unittest.TestCase):
+    def test_join_with_trailing_slashes(self):
+        self.assertEqual(
+            safe_join('http://example.com/', '/path/to'),
+            'http://example.com/path/to'
+        )
+
+    def test_join_without_slashes(self):
+        self.assertEqual(
+            safe_join('http://example.com', 'path/to'),
+            'http://example.com/path/to'
+        )
+
+    def test_base_none(self):
+        self.assertEqual(safe_join(None, 'path'), '')
+
+    def test_base_empty(self):
+        self.assertEqual(safe_join('', 'path'), '')
+
+    def test_tail_empty(self):
+        # joining with empty tail should yield base with trailing slash
+        self.assertEqual(
+            safe_join('http://example.com', ''),
+            'http://example.com/'
+        )
+
+    def test_numeric_base(self):
+        # numeric base is cast to string
+        self.assertEqual(safe_join(123, 'path'), '123/path')
+
+    def test_exception_in_str(self):
+        class Bad:
+            def __str__(self):
+                raise ValueError('bad')
+        # on exception, safe_join returns ''
+        self.assertEqual(safe_join(Bad(), 'x'), '')
+
+if __name__ == '__main__':
+    unittest.main()