diff --git a/server-up/core/boilerplates.py b/server-up/core/boilerplates.py
index ac9a91f..e26b814 100644
--- a/server-up/core/boilerplates.py
+++ b/server-up/core/boilerplates.py
@@ -157,7 +157,12 @@ def _jinja_env():
             block_end_string=_BLK_CLOSE,
             comment_start_string="<#",
             comment_end_string="#>",
-            trim_blocks=True,
+            # trim_blocks=False is cruciaal. De boilerplates gebruiken `<%- ... %>`
+            # waar de `-` zelf al de voorgaande whitespace+newline stript. Als
+            # trim_blocks óók de newline NÁ de tag eet, vloeien opeenvolgende
+            # regels samen tot één regel ("mapping values not allowed in this
+            # context" — homepage, authentik, etc.).
+            trim_blocks=False,
             lstrip_blocks=True,
             keep_trailing_newline=True,
             undefined=ChainableUndefined,