diff --git a/tests/webtbs/tw39646.pp b/tests/webtbs/tw39646.pp
new file mode 100644
index 0000000000..17beb8f22c
--- /dev/null
+++ b/tests/webtbs/tw39646.pp
@@ -0,0 +1,55 @@
+{ %OPT=-O2 }
+program tw39646;
+
+function NestedDivWithAnd(const num: UInt64): Integer;
+  begin
+    NestedDivWithAnd := (num div 100000000) and $FF;
+  end;
+
+function NestedModWithAnd(const num: UInt64): Integer;
+  begin
+    NestedModWithAnd := (num mod 100000000) and $FF;
+  end;
+
+const
+  Input:     array[0..5] of UInt64  = (0, 1, 100000001, 4000000385, 5000000006, 25700000385);
+  ExpectedD: array[0..5] of Integer = (0, 0, 1,         40,         50,         1);
+  ExpectedM: array[0..5] of Integer = (0, 1, 1,         129,        6,          129);
+var
+  Failed: Boolean;
+  X, Output: Integer;
+begin
+  WriteLn('Testing "(UInt64 div 100000000) and $FF" with implicit typecast to Integer:');
+  Failed := False;
+  for X := Low(Input) to High(Input) do
+    begin
+      Write('- Input = ', Input[X], ' ... ');
+      Output := NestedDivWithAnd(Input[X]);
+      if Output = ExpectedD[X] then
+        WriteLn('Passed')
+      else
+        begin
+          WriteLn('FAILED! Got ', Output, ', expected ', ExpectedD[X]);
+          Failed := True;
+        end;
+    end;
+
+  WriteLn(#10'Testing "(UInt64 mod 100000000) and $FF" with implicit typecast to Integer:');
+  for X := Low(Input) to High(Input) do
+    begin
+      Write('- Input = ', Input[X], ' ... ');
+      Output := NestedModWithAnd(Input[X]);
+      if Output = ExpectedM[X] then
+        WriteLn('Passed')
+      else
+        begin
+          WriteLn('FAILED! Got ', Output, ', expected ', ExpectedM[X]);
+          Failed := True;
+        end;
+    end;
+
+  if Failed then
+    Halt(1)
+  else
+    WriteLn('ok');
+end.
\ No newline at end of file