diff --git a/src/animaltrack/web/templates/actions.py b/src/animaltrack/web/templates/actions.py
index b2f276e..c3c63ab 100644
--- a/src/animaltrack/web/templates/actions.py
+++ b/src/animaltrack/web/templates/actions.py
@@ -47,6 +47,7 @@ def event_datetime_field(
     """
     picker_id = f"{field_id}_picker"
     input_id = f"{field_id}_input"
+    ts_utc_id = f"{field_id}_ts_utc"
 
     # If initial value is set, start with picker expanded
     has_initial = bool(initial_value)
@@ -57,7 +58,7 @@ def event_datetime_field(
     toggle_onclick = f"""
         var picker = document.getElementById('{picker_id}');
         var input = document.getElementById('{input_id}');
-        var tsField = document.querySelector('input[name="ts_utc"]');
+        var tsField = document.getElementById('{ts_utc_id}');
         if (picker.style.display === 'none') {{
             picker.style.display = 'block';
             this.textContent = 'Use current time';
@@ -70,14 +71,14 @@ def event_datetime_field(
     """
 
     # Inline JavaScript for input change handler
-    input_onchange = """
-        var tsField = document.querySelector('input[name="ts_utc"]');
-        if (tsField && this.value) {
+    input_onchange = f"""
+        var tsField = document.getElementById('{ts_utc_id}');
+        if (tsField && this.value) {{
             var date = new Date(this.value);
             tsField.value = date.getTime().toString();
-        } else if (tsField) {
+        }} else if (tsField) {{
             tsField.value = '0';
-        }
+        }}
     """
 
     return Div(
@@ -111,7 +112,7 @@ def event_datetime_field(
             ),
             cls="mt-1",
         ),
-        Hidden(name="ts_utc", value=initial_ts),
+        Hidden(id=ts_utc_id, name="ts_utc", value=initial_ts),
         cls="space-y-1",
     )