diff --git a/Source/dwsArrayExprs.pas b/Source/dwsArrayExprs.pas
index 1b09bee4..a46db880 100644
--- a/Source/dwsArrayExprs.pas
+++ b/Source/dwsArrayExprs.pas
@@ -778,14 +778,14 @@ implementation
    // this needs to be in a helper (or more precisely implemented at the top of this unit)
    // otherwise inlining won't work
    TBoundsHelper = class helper for TProgramExpr
-      procedure BoundsCheck(exec : TdwsExecution; aLength, index : Integer); inline;
+      procedure BoundsCheck(exec : TdwsExecution; aLength, index : Int64); inline;
    end;
 
 // BoundsCheck
 //
-procedure TBoundsHelper.BoundsCheck(exec : TdwsExecution; aLength, index : Integer);
+procedure TBoundsHelper.BoundsCheck(exec : TdwsExecution; aLength, index : Int64);
 begin
-   if Cardinal(index)>=Cardinal(aLength) then
+   if UInt64(index)>=UInt64(aLength) then
       BoundsCheckFailed(exec, index);
 end;
 
@@ -1252,7 +1252,7 @@ function TStaticArrayExpr.GetIndex(exec : TdwsExecution) : Int64;
    // Get index
    Result := FIndexExpr.EvalAsInteger(exec) - FLowBound;
 
-   if NativeUInt(Result) >= NativeUInt(FCount) then begin
+   if UInt64(Result) >= UInt64(FCount) then begin
       if Result >= FCount then
          RaiseUpperExceeded(exec, Result + FLowBound)
       else RaiseLowerExceeded(exec, Result + FLowBound);
@@ -1333,7 +1333,7 @@ constructor TOpenArrayExpr.Create(const aScriptPos: TScriptPos;
 //
 procedure TOpenArrayExpr.GetDataPtr(exec : TdwsExecution; var result : IDataContext);
 var
-   index : Integer;
+   index : Int64;
 begin
    index := FIndexExpr.EvalAsInteger(exec);
 
@@ -1647,11 +1647,13 @@ destructor TDynamicArraySetExpr.Destroy;
 procedure TDynamicArraySetExpr.EvalNoResult(exec : TdwsExecution);
 var
    dyn : IScriptDynArray;
-   index : Integer;
+   index : Int64;
 begin
    ArrayExpr.EvalAsScriptDynArray(exec, dyn);
    index := IndexExpr.EvalAsInteger(exec);
-   if not dyn.SetFromExpr(index, exec, ValueExpr) then
+   // bounds-checked here rather than through SetFromExpr: the index is Int64,
+   // but SetFromExpr takes NativeInt, which truncates on 32 bit targets
+   if (not dyn.BoundsCheckPassed(index)) or (not dyn.SetFromExpr(index, exec, ValueExpr)) then
       BoundsCheckFailed(exec, index);
 end;
 
@@ -1696,11 +1698,12 @@ function TDynamicArraySetExpr.GetSubExprCount : Integer;
 procedure TDynamicArraySetVarExpr.EvalNoResult(exec : TdwsExecution);
 var
    p : PIUnknown;
-   index : Integer;
+   index : Int64;
 begin
    p := exec.Stack.PointerToInterfaceValue_BaseRelative(TObjectVarExpr(ArrayExpr).StackAddr);
    index := IndexExpr.EvalAsInteger(exec);
-   if not IScriptDynArray(p^).SetFromExpr(index, exec, ValueExpr) then
+   if (not IScriptDynArray(p^).BoundsCheckPassed(index))
+      or (not IScriptDynArray(p^).SetFromExpr(index, exec, ValueExpr)) then
       BoundsCheckFailed(exec, index);
 end;
 
@@ -1713,7 +1716,7 @@ procedure TDynamicArraySetVarExpr.EvalNoResult(exec : TdwsExecution);
 procedure TDynamicArraySetDataExpr.EvalNoResult(exec : TdwsExecution);
 var
    dynDataArray : TScriptDynamicDataArray;
-   index : Integer;
+   index : Int64;
    base : IScriptDynArray;
    dataExpr : TDataExpr;
 begin
@@ -2095,7 +2098,7 @@ destructor TArraySwapExpr.Destroy;
 //
 procedure TArraySwapExpr.EvalAsScriptDynArray(exec : TdwsExecution; var result : IScriptDynArray);
 var
-   i1, i2 : Integer;
+   i1, i2 : Int64;
 begin
    BaseExpr.EvalAsScriptDynArray(exec, result);
    i1 := Index1Expr.EvalAsInteger(exec);
@@ -3057,7 +3060,7 @@ destructor TArrayDeleteExpr.Destroy;
 procedure TArrayDeleteExpr.EvalNoResult(exec : TdwsExecution);
 var
    base : IScriptDynArray;
-   index, count : Integer;
+   index, count : Int64;
 begin
    BaseExpr.EvalAsScriptDynArray(exec, base);
 
@@ -3132,7 +3135,7 @@ procedure TArrayCopyExpr.EvalAsVariant(exec : TdwsExecution; var Result : Varian
 procedure TArrayCopyExpr.EvalAsScriptDynArray(exec : TdwsExecution; var result : IScriptDynArray);
 var
    base : IScriptDynArray;
-   index, count : Integer;
+   index, count : Int64;
 begin
    BaseExpr.EvalAsScriptDynArray(exec, base);
    if IndexExpr <> nil then begin
@@ -3197,7 +3200,8 @@ destructor TArrayInsertExpr.Destroy;
 procedure TArrayInsertExpr.EvalNoResult(exec : TdwsExecution);
 var
    base : IScriptDynArray;
-   n, index, elemSize : Integer;
+   n, index : Int64;
+   elemSize : Integer;
    buf : Variant;
 begin
    BaseExpr.EvalAsScriptDynArray(exec, base);
@@ -3268,7 +3272,7 @@ destructor TArrayMoveExpr.Destroy;
 procedure TArrayMoveExpr.EvalNoResult(exec : TdwsExecution);
 var
    base : IScriptDynArray;
-   indexOrigin, indexDest : Integer;
+   indexOrigin, indexDest : Int64;
 begin
    BaseExpr.EvalAsScriptDynArray(exec, base);
 
diff --git a/Source/dwsExprs.pas b/Source/dwsExprs.pas
index 4cd95412..b432fab2 100644
--- a/Source/dwsExprs.pas
+++ b/Source/dwsExprs.pas
@@ -709,9 +709,9 @@    TProgramExpr = class(TExprBase)
          procedure AssignValueAsScriptObj(exec : TdwsExecution; const value : IScriptObj); override;
          procedure AssignValueAsScriptDynArray(exec : TdwsExecution; const value : IScriptDynArray); override;
 
-         procedure RaiseUpperExceeded(exec : TdwsExecution; index : Integer);
-         procedure RaiseLowerExceeded(exec : TdwsExecution; index : Integer);
-         procedure BoundsCheckFailed(exec : TdwsExecution; index : Integer);
+         procedure RaiseUpperExceeded(exec : TdwsExecution; index : Int64);
+         procedure RaiseLowerExceeded(exec : TdwsExecution; index : Int64);
+         procedure BoundsCheckFailed(exec : TdwsExecution; index : Int64);
 
          procedure CheckScriptObject(exec : TdwsExecution; const scriptObj : IScriptObj);
 
@@ -3948,21 +3948,21 @@ procedure TProgramExpr.EvalAsUnicodeString(exec : TdwsExecution; var result : Un
 
 // RaiseUpperExceeded
 //
-procedure TProgramExpr.RaiseUpperExceeded(exec : TdwsExecution; index : Integer);
+procedure TProgramExpr.RaiseUpperExceeded(exec : TdwsExecution; index : Int64);
 begin
    RaiseScriptError(exec, EScriptOutOfBounds.CreateFmt(RTE_ArrayUpperBoundExceeded, [index]));
 end;
 
 // RaiseLowerExceeded
 //
-procedure TProgramExpr.RaiseLowerExceeded(exec : TdwsExecution; index : Integer);
+procedure TProgramExpr.RaiseLowerExceeded(exec : TdwsExecution; index : Int64);
 begin
    RaiseScriptError(exec, EScriptOutOfBounds.CreateFmt(RTE_ArrayLowerBoundExceeded, [index]));
 end;
 
 // BoundsCheckFailed
 //
-procedure TProgramExpr.BoundsCheckFailed(exec : TdwsExecution; index : Integer);
+procedure TProgramExpr.BoundsCheckFailed(exec : TdwsExecution; index : Int64);
 begin
    if index < 0 then
       RaiseLowerExceeded(exec, index)
diff --git a/Test/ArrayPass/array_bounds_int64.pas b/Test/ArrayPass/array_bounds_int64.pas
index 63596530..345e8655 100644
--- a/Test/ArrayPass/array_bounds_int64.pas
+++ b/Test/ArrayPass/array_bounds_int64.pas
@@ -48,3 +48,54 @@ function MakeArr : array of Integer;
 end;
 
 PrintLn(a[2]);
+
+var d : array of Integer;
+d.SetLength(5);
+for var i := 0 to 4 do
+   d[i] := 200 + i;
+
+try
+   d[base + 1] := 999;
+   PrintLn('FAIL no exception on dynamic write (d[2^32 + 1])');
+except
+   on E: Exception do PrintLn('OK out-of-bounds raised on dynamic write');
+end;
+
+PrintLn(d[1]);
+
+try
+   d.Delete(base);
+   PrintLn('FAIL no exception (d.Delete(2^32))');
+except
+   on E: Exception do PrintLn('OK out-of-bounds raised for Delete');
+end;
+
+try
+   d.Insert(base, 1);
+   PrintLn('FAIL no exception (d.Insert(2^32))');
+except
+   on E: Exception do PrintLn('OK out-of-bounds raised for Insert');
+end;
+
+try
+   d.Swap(base, 1);
+   PrintLn('FAIL no exception (d.Swap(2^32, 1))');
+except
+   on E: Exception do PrintLn('OK out-of-bounds raised for Swap');
+end;
+
+try
+   d.Move(base, 1);
+   PrintLn('FAIL no exception (d.Move(2^32, 1))');
+except
+   on E: Exception do PrintLn('OK out-of-bounds raised for Move');
+end;
+
+try
+   PrintLn(d.Copy(base, 1).Length);
+   PrintLn('FAIL no exception (d.Copy(2^32, 1))');
+except
+   on E: Exception do PrintLn('OK out-of-bounds raised for Copy');
+end;
+
+PrintLn(d.Length);
diff --git a/Test/ArrayPass/array_bounds_int64.txt b/Test/ArrayPass/array_bounds_int64.txt
index a0958cc6..67b0fc4e 100644
--- a/Test/ArrayPass/array_bounds_int64.txt
+++ b/Test/ArrayPass/array_bounds_int64.txt
@@ -4,3 +4,11 @@ OK out-of-bounds raised for 2^32
 OK out-of-bounds raised for 2^32 + 3
 OK out-of-bounds raised on write
 102
+OK out-of-bounds raised on dynamic write
+201
+OK out-of-bounds raised for Delete
+OK out-of-bounds raised for Insert
+OK out-of-bounds raised for Swap
+OK out-of-bounds raised for Move
+OK out-of-bounds raised for Copy
+5