diff --git a/solvers/UParabolicReflectorDish.pas b/solvers/UParabolicReflectorDish.pas
index 183db38..f62740e 100644
--- a/solvers/UParabolicReflectorDish.pas
+++ b/solvers/UParabolicReflectorDish.pas
@@ -27,6 +27,7 @@ uses
 const
   CRoundRockChar = 'O';
   CCubeRockChar = '#';
+  CEmptyChar = '.';
   CMaxSpinCount = 1000000000;
 
 type
@@ -56,6 +57,7 @@ type
     procedure TiltWest;
     procedure TiltEast;
     function IsEqualTo(const FOther: TStringList): Boolean;
+    procedure SwapRockLocation(const AColumn, ARockLineIndex, AEmptyLineIndex: Integer);
   public
     constructor Create;
     destructor Destroy; override;
@@ -115,50 +117,34 @@ end;
 procedure TPlatform.TiltNorth;
 var
   i, j, k: Integer;
-  s: string;
 begin
   for i := 0 to FLines.Count - 1 do
     for j := 1 to Length(FLines[i]) do
       if FLines[i][j] = CRoundRockChar then
       begin
         k := i - 1;
-        while (k >= 0) and (FLines[k][j] = '.') do
+        while (k >= 0) and (FLines[k][j] = CEmptyChar) do
           Dec(k);
         Inc(k);
         if k < i then
-        begin
-          s := FLines[i];
-          s[j] := '.';
-          FLines[i] := s;
-          s := FLines[k];
-          s[j] := CRoundRockChar;
-          FLines[k] := s;
-        end;
+          SwapRockLocation(j, i, k);
       end;
 end;
 
 procedure TPlatform.TiltSouth;
 var
   i, j, k: Integer;
-  s: string;
 begin
   for i := FLines.Count - 1 downto 0 do
     for j := 1 to Length(FLines[i]) do
       if FLines[i][j] = CRoundRockChar then
       begin
         k := i + 1;
-        while (k < FLines.Count) and (FLines[k][j] = '.') do
+        while (k < FLines.Count) and (FLines[k][j] = CEmptyChar) do
           Inc(k);
         Dec(k);
         if k > i then
-        begin
-          s := FLines[i];
-          s[j] := '.';
-          FLines[i] := s;
-          s := FLines[k];
-          s[j] := CRoundRockChar;
-          FLines[k] := s;
-        end;
+          SwapRockLocation(j, i, k);
       end;
 end;
 
@@ -174,14 +160,14 @@ begin
     for j := 1 to Length(s) do
     begin
       case s[j] of
-        '.':
+        CEmptyChar:
           if k <= 0 then
             k := j;
         CRoundRockChar: begin
           if (k > 0) and (k < j) then
           begin
             s[k] := CRoundRockChar;
-            s[j] := '.';
+            s[j] := CEmptyChar;
             Inc(k);
           end
           else
@@ -206,14 +192,14 @@ begin
     for j := Length(s) downto 1 do
     begin
       case s[j] of
-        '.':
+        CEmptyChar:
           if k > Length(s) then
             k := j;
         CRoundRockChar: begin
           if (k <= Length(s)) and (j < k) then
           begin
             s[k] := CRoundRockChar;
-            s[j] := '.';
+            s[j] := CEmptyChar;
             Dec(k);
           end
           else
@@ -241,7 +227,20 @@ begin
       end;
   end
   else
-    Result := False;end;
+    Result := False;
+end;
+
+procedure TPlatform.SwapRockLocation(const AColumn, ARockLineIndex, AEmptyLineIndex: Integer);
+var
+  s: string;
+begin
+  s := FLines[ARockLineIndex];
+  s[AColumn] := CEmptyChar;
+  FLines[ARockLineIndex] := s;
+  s := FLines[AEmptyLineIndex];
+  s[AColumn] := CRoundRockChar;
+  FLines[AEmptyLineIndex] := s;
+end;
 
 constructor TPlatform.Create;
 begin