diff --git a/lib/filter/src/fir_iterative_pkg.vhd b/lib/filter/src/fir_iterative_pkg.vhd
index c00d0cf..af8bb68 100644
--- a/lib/filter/src/fir_iterative_pkg.vhd
+++ b/lib/filter/src/fir_iterative_pkg.vhd
@@ -29,7 +29,7 @@ package body fir_iterative_pkg is
 	function taps_nbits(ntaps : integer; mode : fir_iterative_mode_t) return integer is
 	variable res : integer;
 	begin
-		res := integer(NextPowerOfTwo(real(ntaps_addr(ntaps, mode))));
+		res := integer(NextExpBaseTwo(real(ntaps_addr(ntaps, mode))));
 		return res;
 	end taps_nbits;