diff --git a/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/internal/spigot/recipes/listeners/ComplexInEco.kt b/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/internal/spigot/recipes/listeners/ComplexInEco.kt
index 5047c648..d115f12f 100644
--- a/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/internal/spigot/recipes/listeners/ComplexInEco.kt
+++ b/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/internal/spigot/recipes/listeners/ComplexInEco.kt
@@ -26,7 +26,7 @@ class ComplexInEco : RecipeListener {
         }
 
         for (i in 0..8) {
-            val itemStack = event.inventory.matrix[i]
+            val itemStack = event.inventory.matrix[i] ?: continue
             val part = craftingRecipe.parts[i]
             if (part.isCustomWhenShouldNotBe(itemStack)) {
                 event.deny()