diff --git a/wetter/utils.py b/wetter/utils.py
new file mode 100644
index 0000000..e59ea25
--- /dev/null
+++ b/wetter/utils.py
@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+
+from datetime import datetime
+
+def fromisoformat(str):
+    return datetime.strptime(str, '%Y-%m-%d').date()
diff --git a/wetter/views.py b/wetter/views.py
index 1435a1d..4f33632 100644
--- a/wetter/views.py
+++ b/wetter/views.py
@@ -2,6 +2,7 @@
 
 from wetter import app
 from wetter.models import Stations, Climate
+from wetter.utils import fromisoformat
 from flask import request, make_response, render_template
 from datetime import datetime
 
@@ -33,38 +34,38 @@ def export(dwd_id):
 
 @app.route('/station/<dwd_id>/export/target/')
 def export_target(dwd_id):
-    fr = request.args.get('from')
-    to = request.args.get('to')
+    fr = fromisoformat(request.args.get('from'))
+    to = fromisoformat(request.args.get('to'))
 
     station = Stations.query.filter_by(dwd_id=dwd_id).first_or_404()
 
-    return render_template('target.html', station=station, fr=fr, to=to)
+    return render_template('target.html', station=station, fr=fr.isoformat(), to=to.isoformat())
 
 @app.route('/station/<dwd_id>/export/target/ce.csv/')
 def export_target_ce_csv_render(dwd_id):
-    fr = request.args.get('from')
-    to = request.args.get('to')
+    fr = fromisoformat(request.args.get('from'))
+    to = fromisoformat(request.args.get('to'))
 
     station = Stations.query.filter_by(dwd_id=dwd_id).first_or_404()
-    climate = Climate.query.filter_by(station=station.id).filter(Climate.date >= fr, Climate.date <= to).order_by(Climate.date.asc())
+    climate = Climate.query.filter_by(station=station.id).filter(Climate.date >= fr.isoformat(), Climate.date <= to.isoformat()).order_by(Climate.date.asc())
 
     r = make_response(render_template('export/ce.csv', climate=climate))
     r.headers['Content-Type'] = 'text/csv; charset=utf-8'
-    r.headers['Content-Disposition'] = 'attachment; filename="wetter_' +station.dwd_id +'_' + fr + '_' + to +'_ce.csv'
+    r.headers['Content-Disposition'] = 'attachment; filename="wetter_' +station.dwd_id +'_' + fr.isoformat() + '_' + to.isoformat() +'_ce.csv'
 
     return r
 
 @app.route('/station/<dwd_id>/export/target/dwd.txt/')
 def export_target_dwd_txt_render(dwd_id):
-    fr = request.args.get('from')
-    to = request.args.get('to')
+    fr = fromisoformat(request.args.get('from'))
+    to = fromisoformat(request.args.get('to'))
 
     station = Stations.query.filter_by(dwd_id=dwd_id).first_or_404()
-    climate = Climate.query.filter_by(station=station.id).filter(Climate.date >= fr, Climate.date <= to).order_by(Climate.date.asc())
+    climate = Climate.query.filter_by(station=station.id).filter(Climate.date >= fr.isoformat(), Climate.date <= to.isoformat()).order_by(Climate.date.asc())
 
     r = make_response(render_template('export/dwd.txt', station=station, climate=climate))
     r.headers['Content-Type'] = 'text/txt; charset=utf-8'
-    r.headers['Content-Disposition'] = 'attachment; filename="wetter_' + station.dwd_id +'_' + fr + '_' + to +'_dwd.txt'
+    r.headers['Content-Disposition'] = 'attachment; filename="wetter_' + station.dwd_id +'_' + fr.isoformat() + '_' + to.isoformat() +'_dwd.txt'
 
     return r