diff --git a/code/__DEFINES/combat.dm b/code/__DEFINES/combat.dm
index 66bea5b01c8..4a483268e81 100644
--- a/code/__DEFINES/combat.dm
+++ b/code/__DEFINES/combat.dm
@@ -355,7 +355,7 @@ GLOBAL_LIST_INIT(all_precise_body_zones, list(BODY_ZONE_PRECISE_EYES, BODY_ZONE_
 /// Armor can't block more than this as a percentage
 #define ARMOR_MAX_BLOCK 90
 /// Calculates the new armour value after armour penetration. Can return negative values, and those must be caught.
-#define PENETRATE_ARMOUR(armour, penetration) (penetration == 100 ? 0 : 100 * (armour - penetration) / (100 - penetration))
+#define PENETRATE_ARMOUR(armour, penetration) (penetration >= 100 ? 0 : 100 * (armour - penetration) / (100 - penetration))
 
 // Defines for combo attack component
 /// LMB Attack