diff --git a/src/Library/TypeLibrary.cpp b/src/Library/TypeLibrary.cpp
index 220a16b..75250fa 100644
--- a/src/Library/TypeLibrary.cpp
+++ b/src/Library/TypeLibrary.cpp
@@ -5,7 +5,9 @@
 using namespace CreatureLib::Library;
 
 float TypeLibrary::GetEffectiveness(uint8_t attacking, const List<uint8_t>& defensive) const {
-    return std::accumulate(defensive.begin(), defensive.end(), (float)1, std::multiplies<float>());
+    return std::accumulate(
+        defensive.begin(), defensive.end(), (float)1,
+        [this, attacking](float init, uint8_t defense) { return init * GetSingleEffectiveness(attacking, defense); });
 }
 
 float TypeLibrary::GetSingleEffectiveness(uint8_t attacking, uint8_t defensive) const {