diff --git a/src/population.rs b/src/population.rs
index 6a97d9b..c63ef11 100644
--- a/src/population.rs
+++ b/src/population.rs
@@ -447,12 +447,14 @@ mod tests {
         println!("Population after generate: {:?}", stats);
 
         // total * proba - 20% < infected < total * proba + 20%
-        let infected_at_start = width * height * start_infected as i32 / 100;
+        let infected_at_start_proba = width * height * start_infected as i32 / 100;
         let infected_tolerance = ((width * height) as f32 * 0.2) as i32;
-        assert!(stats.infected < infected_at_start + infected_tolerance);
-        assert!(stats.infected > infected_at_start - infected_tolerance);
+        assert!(stats.infected < infected_at_start_proba + infected_tolerance);
+        assert!(stats.infected > infected_at_start_proba - infected_tolerance);
         assert_eq!(stats.dead, 0);
 
+        let infected_at_start = stats.infected;
+
         population.propagate();
         stats = humans_stats(&population.humans);
         println!("Population after propagate: {:?}", stats);