diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/compat/ExtendedInventoryHandler.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/compat/ExtendedInventoryHandler.kt
index 72d05fb96..0ea13d42d 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/compat/ExtendedInventoryHandler.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/compat/ExtendedInventoryHandler.kt
@@ -44,7 +44,7 @@ private class MenuConfiguration(
 
 			val matteryPlayer = player.matteryPlayer ?: return
 
-			if (!matteryPlayer.hasExoSuit || matteryPlayer.exoSuitContainer.containerSize <= value * 9) {
+			if (!matteryPlayer.hasExoSuit || matteryPlayer.exoSuitContainer.containerSize <= (value - 1) * 9) {
 				return
 			}