diff --git a/worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java b/worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java
index 410cc5d9e1..ca43de5857 100644
--- a/worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java
+++ b/worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java
@@ -371,6 +371,8 @@ public int stack(Actor actor, World world, EditSession editSession, LocalSession
                         boolean blockUnits,
                      @ArgFlag(name = 'm', desc = "Set the include mask, non-matching blocks become air")
                          Mask mask) throws WorldEditException {
+        checkCommandArgument(count >= 1, "Count must be >= 1");
+
         Mask combinedMask;
         if (ignoreAirBlocks) {
             if (mask == null) {