diff --git a/src/js/game/systems/filter.js b/src/js/game/systems/filter.js
index 09a68174..547b3e6c 100644
--- a/src/js/game/systems/filter.js
+++ b/src/js/game/systems/filter.js
@@ -19,8 +19,7 @@ export class FilterSystem extends GameSystemWithFilter {
             // Take items from acceptor
             const input = acceptorComp.completedInputs[0];
             if (input && this.tryAcceptItem(entity, input.item, input.extraProgress)) {
-                // only remove one
-                acceptorComp.completedInputs.splice(0);
+                acceptorComp.completedInputs.shift();
             }
 
             // Output to ejector
diff --git a/src/js/game/systems/underground_belt.js b/src/js/game/systems/underground_belt.js
index 45b39ff5..aa3df6cc 100644
--- a/src/js/game/systems/underground_belt.js
+++ b/src/js/game/systems/underground_belt.js
@@ -323,7 +323,7 @@ export class UndergroundBeltSystem extends GameSystemWithFilter {
                     input.extraProgress
                 )
             ) {
-                acceptorComp.completedInputs.splice(0);
+                acceptorComp.completedInputs.shift();
             }
         }
     }