diff --git a/qgreenland/models/config/layer.py b/qgreenland/models/config/layer.py
index 042e523c..a0c05f60 100644
--- a/qgreenland/models/config/layer.py
+++ b/qgreenland/models/config/layer.py
@@ -1,5 +1,6 @@
 from pathlib import Path
 from typing import Any, Optional, Union
+from xml.etree import ElementTree
 
 from pydantic import Field, validator
 
@@ -57,6 +58,24 @@ class Layer(QgrBaseModel):
 
     _validate_description = reusable_validator("description", validate_paragraph_text)
 
+    @validator("style")
+    @classmethod
+    def style_file_only_contains_allowed_fonts(cls, value):
+        allowed_fonts = ["Open Sans"]
+        if value:
+            style_filepath = _style_filepath(value)
+            tree = ElementTree.parse(style_filepath)
+            for elem in tree.getroot().iter():
+                if font_family := elem.attrib.get("fontFamily", False):
+                    if font_family not in allowed_fonts:
+                        raise exc.QgrInvalidConfigError(
+                            f"Style {style_filepath} contains disallowed font:"
+                            f" '{font_family}'."
+                            f" Only the following fonts are allowed: {allowed_fonts}."
+                        )
+
+        return value
+
     @validator("style")
     @classmethod
     def style_file_exists(cls, value):