diff --git a/lightning/src/routing/scoring.rs b/lightning/src/routing/scoring.rs
index 4fb8d8ba7d4..ad49bf76259 100644
--- a/lightning/src/routing/scoring.rs
+++ b/lightning/src/routing/scoring.rs
@@ -1192,7 +1192,7 @@ fn success_probability(
 
 			// Because our numerator and denominator max out at 0.0078125 we need to multiply them
 			// by quite a large factor to get something useful (ideally in the 2^30 range).
-			const BILLIONISH: f64 = 32.0 * 1024.0 * 1024.0 * 1024.0;
+			const BILLIONISH: f64 = 16.0 * 1024.0 * 1024.0 * 1024.0;
 			let numerator = (num * BILLIONISH) as u64 + 1;
 			let denominator = (den * BILLIONISH) as u64 + 1;
 			debug_assert!(numerator <= 1 << 30, "Got large numerator ({}) from float {}.", numerator, num);