Index: /Include/Classes/System/Math.ab
===================================================================
--- /Include/Classes/System/Math.ab	(revision 52)
+++ /Include/Classes/System/Math.ab	(revision 53)
@@ -500,15 +500,15 @@
 
 	Static Function Sin(value As Double) As Double
-		If IsNaN(number) Then
-			Return number
-		ElseIf IsInf(number) Then
+		If IsNaN(value) Then
+			Return value
+		ElseIf IsInf(value) Then
 			Return _System_GetNaN()
 			Exit Function
 		End If
 
-		Dim k As Integer
+		Dim k As Long
 		Dim t As Double
 
-		t = urTan(x * 0.5, k)
+		t = urTan(value * 0.5, k)
 		t = 2 * t / (1 + t * t)
 		If (k And 1) = 0 Then 'k mod 2 = 0 Then
@@ -587,11 +587,9 @@
 	End Function
 
-	'ToString
-
 	Static Function Truncate(x As Double) As Double
 		return Fix(x)
 	End Function
 
-'Private
+Private
 	Static Function urTan(x As Double, ByRef k As Long) As Double
 		Dim i As Long
@@ -599,7 +597,7 @@
 
 		If x >= 0 Then
-			k = Fix(x * _System_InverseHalfPI) + 0.5
-		Else
-			k = Fix(x * _System_InverseHalfPI) - 0.5
+			k = ( ( Fix(x * _System_InverseHalfPI) As Double ) + 0.5 ) As Long
+		Else
+			k = ( ( Fix(x * _System_InverseHalfPI) As Double ) - 0.5 ) As Long
 		End If
 		x = (x - (3217.0 / 2048.0) * k) + _System_D * k