diff --git a/components/fpspreadsheet/source/common/fpsexprparser.pas b/components/fpspreadsheet/source/common/fpsexprparser.pas
index 8a033784f..3ee0306f6 100644
--- a/components/fpspreadsheet/source/common/fpsexprparser.pas
+++ b/components/fpspreadsheet/source/common/fpsexprparser.pas
@@ -295,6 +295,8 @@ type
     constructor Create(AParser: TsExpressionParser; AOperand: TsExprNode);
     procedure Check; override;
     destructor Destroy; override;
+    procedure IterateNodes(AProc: TsExprNodeProc; AData1, AData2: Pointer;
+      var MustRebuildFormulas: boolean); override;
     property Operand: TsExprNode read FOperand;
   end;
 
@@ -2948,6 +2950,12 @@ begin
     RaiseParserError(rsNoOperand, [Self.ClassName]);
 end;
 
+procedure TsUnaryOperationExprNode.IterateNodes(AProc: TsExprNodeProc;
+  AData1, AData2: Pointer; var MustRebuildFormulas: Boolean);
+begin
+  FOperand.IterateNodes(AProc, AData1, AData2, MustRebuildFormulas);
+end;
+
 
 { TsBinaryOperationExprNode }