diff --git a/src/main/scala/millfork/OptimizationPresets.scala b/src/main/scala/millfork/OptimizationPresets.scala
index a8616754..ed437c0b 100644
--- a/src/main/scala/millfork/OptimizationPresets.scala
+++ b/src/main/scala/millfork/OptimizationPresets.scala
@@ -46,6 +46,7 @@ object OptimizationPresets {
     AlwaysGoodOptimizations.PointlessOperationAfterLoad,
     AlwaysGoodOptimizations.IdempotentDuplicateRemoval,
     LoopUnrolling.LoopUnrolling,
+    AlwaysGoodOptimizations.ConstantPointer,
     AlwaysGoodOptimizations.ConstantIndexPropagation,
     AlwaysGoodOptimizations.PointlessLoadBeforeReturn,
     AlwaysGoodOptimizations.PoinlessFlagChange,
@@ -67,9 +68,11 @@ object OptimizationPresets {
     LaterOptimizations.DoubleLoadToTheSameRegister,
     LaterOptimizations.DoubleLoadToTwoRegistersWhenOneWillBeTrashed,
     EmptyMemoryStoreRemoval,
+    EmptyParameterStoreRemoval,
     AlwaysGoodOptimizations.PointlessOperationFromFlow,
     AlwaysGoodOptimizations.PoinlessLoadBeforeAnotherLoad,
     AlwaysGoodOptimizations.IdempotentDuplicateRemoval,
+    AlwaysGoodOptimizations.ConstantPointer,
     AlwaysGoodOptimizations.ConstantIndexPropagation,
     AlwaysGoodOptimizations.ConstantFlowAnalysis,
     AlwaysGoodOptimizations.PointlessRegisterTransfers,
@@ -86,6 +89,7 @@ object OptimizationPresets {
     AlwaysGoodOptimizations.RearrangeMath,
     AlwaysGoodOptimizations.LoadingOfJustWrittenValue,
     EmptyMemoryStoreRemoval,
+    EmptyParameterStoreRemoval,
     AlwaysGoodOptimizations.PointlessLoadBeforeReturn,
     LaterOptimizations.PointessLoadingForShifting,
     AlwaysGoodOptimizations.SimplifiableBitOpsSequence,
@@ -95,6 +99,7 @@ object OptimizationPresets {
 
     LaterOptimizations.LoadingAfterShifting,
     EmptyMemoryStoreRemoval,
+    EmptyParameterStoreRemoval,
     AlwaysGoodOptimizations.PoinlessStoreBeforeStore,
     LaterOptimizations.PointlessLoadAfterStore,
     AlwaysGoodOptimizations.PoinlessLoadBeforeAnotherLoad,
@@ -105,6 +110,7 @@ object OptimizationPresets {
 
     LaterOptimizations.LoadingAfterShifting,
     EmptyMemoryStoreRemoval,
+    EmptyParameterStoreRemoval,
     AlwaysGoodOptimizations.PoinlessStoreBeforeStore,
     LaterOptimizations.PointlessLoadAfterStore,
     AlwaysGoodOptimizations.PoinlessLoadBeforeAnotherLoad,
@@ -112,7 +118,9 @@ object OptimizationPresets {
     LaterOptimizations.LoadingAfterShifting,
     AlwaysGoodOptimizations.PointlessAccumulatorShifting,
     EmptyMemoryStoreRemoval,
+    EmptyParameterStoreRemoval,
     AlwaysGoodOptimizations.PoinlessStoreBeforeStore,
+    AlwaysGoodOptimizations.ConstantPointer,
     LaterOptimizations.PointlessLoadAfterStore,
     AlwaysGoodOptimizations.PoinlessLoadBeforeAnotherLoad,
     AlwaysGoodOptimizations.TailCallOptimization,
@@ -135,6 +143,7 @@ object OptimizationPresets {
     AlwaysGoodOptimizations.PointlessStackStore,
     AlwaysGoodOptimizations.OptimizeZeroComparisons,
     AlwaysGoodOptimizations.SimplifiableCondition,
+    AlwaysGoodOptimizations.ConstantPointer,
     AlwaysGoodOptimizations.IncrementingIndexRegistersAfterTransfer,
     AlwaysGoodOptimizations.MathOperationOnTwoIdenticalMemoryOperands,
     LaterOptimizations.UseZeropageAddressingMode,
@@ -167,6 +176,7 @@ object OptimizationPresets {
     AlwaysGoodOptimizations.ConstantIndexPropagation,
     AlwaysGoodOptimizations.DoubleJumpSimplification,
     EmptyMemoryStoreRemoval,
+    EmptyParameterStoreRemoval,
     AlwaysGoodOptimizations.FlagFlowAnalysis,
     AlwaysGoodOptimizations.IdempotentDuplicateRemoval,
     AlwaysGoodOptimizations.ImpossibleBranchRemoval,
diff --git a/src/main/scala/millfork/assembly/mos/opt/EmptyParameterStoreRemoval.scala b/src/main/scala/millfork/assembly/mos/opt/EmptyParameterStoreRemoval.scala
new file mode 100644
index 00000000..d0b4385f
--- /dev/null
+++ b/src/main/scala/millfork/assembly/mos/opt/EmptyParameterStoreRemoval.scala
@@ -0,0 +1,80 @@
+package millfork.assembly.mos.opt
+
+import millfork.assembly.mos.AddrMode._
+import millfork.assembly.mos.AssemblyLine
+import millfork.assembly.mos.Opcode._
+import millfork.assembly.{AssemblyOptimization, OptimizationContext}
+import millfork.env._
+import millfork.error.ErrorReporting
+
+/**
+  * @author Karol Stasiak
+  */
+object EmptyParameterStoreRemoval extends AssemblyOptimization[AssemblyLine] {
+  override def name = "Removing pointless stores to foreign variables"
+
+  private val storeInstructions = Set(STA, STX, STY, SAX, STZ, STA_W, STX_W, STY_W, STZ_W)
+  private val storeAddrModes = Set(Absolute, ZeroPage, AbsoluteX, AbsoluteY, ZeroPageX, ZeroPageY)
+
+  override def optimize(f: NormalFunction, code: List[AssemblyLine], optimizationContext: OptimizationContext): List[AssemblyLine] = {
+    val usedFunctions = code.flatMap {
+      case AssemblyLine(JSR | BSR | JMP, _, MemoryAddressConstant(th), _) => Some(th.name)
+      case AssemblyLine(JSR | BSR | JMP, _, NumericConstant(addr, _), _) => Some("$" + addr.toHexString)
+      case _ => None
+    }.toSet
+    val foreignVariables = f.environment.root.things.values.flatMap {
+      case other: NormalFunction =>
+        val address = other.address match {
+          case Some(NumericConstant(addr, _)) => "$" + addr.toHexString
+          case _ => ""
+        }
+        if (other.name == f.name || usedFunctions(other.name) || usedFunctions(address)) {
+          Nil
+        } else {
+          val params = other.params match {
+            case NormalParamSignature(ps) => ps.map(_.name)
+            case _ => Nil
+          }
+          val locals = other.environment.things.values.flatMap{
+            case th: MemoryVariable if th.alloc == VariableAllocationMethod.Auto => Some(th.name)
+            case th: MemoryVariable if th.alloc == VariableAllocationMethod.Zeropage => Some(th.name) // TODO: ???
+            case _ => None
+          }
+          params ++ locals
+        }
+      case _ => Nil
+    }.toSet
+    val stillReadOrStoredVariables = code.flatMap {
+      case AssemblyLine(_, _, MemoryAddressConstant(th), _) => Some(th.name)
+      case AssemblyLine(_, _, CompoundConstant(_, MemoryAddressConstant(th), _), _) => Some(th.name)
+      case AssemblyLine(_, Immediate, SubbyteConstant(MemoryAddressConstant(th), _), _) => Some(th.name)
+      case _ => None
+    }.toSet
+    val stillReadVariables = code.flatMap {
+      case AssemblyLine(op, am, MemoryAddressConstant(th), true)
+        if storeInstructions(op) && storeAddrModes(am) => Nil
+      case AssemblyLine(op, am, CompoundConstant(MathOperator.Plus, MemoryAddressConstant(th), NumericConstant(_, _)), true)
+        if storeInstructions(op) && storeAddrModes(am) => Nil
+      case AssemblyLine(_, _, MemoryAddressConstant(th), _) => Some(th.name)
+      case AssemblyLine(_, _, CompoundConstant(_, MemoryAddressConstant(th), _), _) => Some(th.name)
+      case AssemblyLine(_, Immediate, SubbyteConstant(MemoryAddressConstant(th), _), _) => Some(th.name)
+      case _ => None
+    }.toSet
+
+    val unusedForeignVariables = (foreignVariables & stillReadOrStoredVariables) -- stillReadVariables
+    if (unusedForeignVariables.isEmpty) {
+      return code
+    }
+
+    ErrorReporting.debug(s"Removing pointless store(s) to foreign variables ${unusedForeignVariables.mkString(", ")}")
+    code.filterNot {
+      case AssemblyLine(op, am, MemoryAddressConstant(th), _)
+        if storeInstructions(op) && storeAddrModes(am) =>
+        unusedForeignVariables(th.name)
+      case AssemblyLine(op, am, CompoundConstant(MathOperator.Plus, MemoryAddressConstant(th), NumericConstant(_, _)), true)
+        if storeInstructions(op) && storeAddrModes(am) =>
+        unusedForeignVariables(th.name)
+      case _ => false
+    }
+  }
+}