diff --git a/js/medicine/utility.js b/js/medicine/utility.js
index a7e2ba4d7cd20a6b08d4fb70db9883b0643661bb..07682ad63cc4a404a6ece4947b35515719de8d52 100644
--- a/js/medicine/utility.js
+++ b/js/medicine/utility.js
@@ -29,7 +29,7 @@ App.Medicine.pocketVolume = function() {
 		// now the current skin area:
 		const A = Math.PI * (a * a + h * h);
 
-		const skinStretchFactor = linearInterpolation(Math.max(slave.physicalAge, 13), 13, 1.5, 45, 1.15);
+		const skinStretchFactor = linearInterpolation(Math.clamp(slave.physicalAge, 13, 45), 13, 1.5, 45, 1.15);
 
 		const hMax = Math.sqrt(A * skinStretchFactor / Math.PI - a * a);
 		const VMax = Math.PI / 6 * hMax * (3 * a * a + hMax * hMax);