diff --git a/src/bilirubin_app.js b/src/bilirubin_app.js
index b21813c..f5d8009 100644
--- a/src/bilirubin_app.js
+++ b/src/bilirubin_app.js
@@ -133,11 +133,11 @@ function updateBilirubin() {
 	let bilirubin = document.getElementById('bilirubin').valueAsNumber;
 	let gestation = document.getElementById('gestation').valueAsNumber;
 	
-	if (document.getElementById('time_birth').valueAsDate === null) {
+	if (document.getElementById('time_birth').value === '') {
 		resultDiv.className = 'hidden';
 		return;
 	}
-	if (document.getElementById('time_measurement').valueAsDate === null) {
+	if (document.getElementById('time_measurement').value === '') {
 		resultDiv.className = 'hidden';
 		return;
 	}
@@ -150,7 +150,7 @@ function updateBilirubin() {
 		return;
 	}
 	
-	let [d, result_text, text_colour, background_colour, accent_colour] = describeBilirubin(gestation, document.getElementById('time_birth').valueAsDate, document.getElementById('time_measurement').valueAsDate, bilirubin);
+	let [d, result_text, text_colour, background_colour, accent_colour] = describeBilirubin(gestation, new Date(document.getElementById('time_birth').value), new Date(document.getElementById('time_measurement').value), bilirubin);
 	
 	chart.data.datasets[2].data = [{x: d, y: bilirubin}];
 	chart.update();