diff --git a/analysis/render_report.py b/analysis/render_report.py
index e786df4..70a587c 100644
--- a/analysis/render_report.py
+++ b/analysis/render_report.py
@@ -58,14 +58,9 @@ def b64encode(path):
     return f"data:{mtype};base64, {encoded}"
 
 
-def date_format(date):
-    """Formats the given date as, for example, "1 January 2023"."""
-    return f"{date:%-d %B %Y}"  # the - removes the leading zero, but not on Windows
-
-
 # register template filters
 ENVIRONMENT.filters["b64encode"] = b64encode
-ENVIRONMENT.filters["date_format"] = date_format
+ENVIRONMENT.filters["date_format"] = utils.date_format
 
 
 def render_report(data):
diff --git a/analysis/utils.py b/analysis/utils.py
index 2daf557..e9d2729 100644
--- a/analysis/utils.py
+++ b/analysis/utils.py
@@ -27,3 +27,8 @@ def slugify(s):
     # remove leading and trailing dashes and underscores
     s = s.strip("-_")
     return s.lower()
+
+
+def date_format(date):
+    """Formats the given date as, for example, "1 January 2023"."""
+    return f"{date:%-d %B %Y}"  # the - removes the leading zero, but not on Windows