diff --git a/src/bilirubin_lib.js b/src/bilirubin_lib.js
index b407adb..f29d6b2 100644
--- a/src/bilirubin_lib.js
+++ b/src/bilirubin_lib.js
@@ -79,14 +79,24 @@ function exchange_thresh(d, gestation) {
 // --------------
 // Utility functions
 
+function prettyPrintHours(d) {
+	if (d < 0.5/24) {
+		return '0 hours';
+	}
+	if (d < 1.5/24) {
+		return '1 hour';
+	}
+	return (d * 24).toFixed(0) + ' hours';
+}
+
 function prettyPrintDays(d) {
 	if (d < 1) {
-		return (d * 24).toFixed(0) + ' hours';
+		return prettyPrintHours(d);
 	}
 	if (d < 2) {
-		return '1 day, ' + ((d % 1) * 24).toFixed(0) + ' hours';
+		return '1 day, ' + prettyPrintHours(d % 1);
 	}
-	return Math.floor(d) + ' days, ' + ((d % 1) * 24).toFixed(0) + ' hours';
+	return Math.floor(d) + ' days, ' + prettyPrintHours(d % 1);
 }
 
 function prettyPrintBilirubin(b) {