diff --git a/lib/filter/src/delay_line.vhd b/lib/filter/src/delay_line.vhd
index 5c6bff6..867c1b6 100644
--- a/lib/filter/src/delay_line.vhd
+++ b/lib/filter/src/delay_line.vhd
@@ -64,7 +64,7 @@ begin
 	addr_w	<= to_unsigned(count, addr_w'length);
 	addr_r	<= addr_w + not to_unsigned(delay, addr_w'length);
 	
-	ram_w	<= unsigned(din);
+	ram_w	<= unsigned(to_signed(din));
 	dout	<= sfixed(ram_r);
 
 counter:
diff --git a/lib/filter/src/fir_semi_parallel.vhd b/lib/filter/src/fir_semi_parallel.vhd
index 2db3f73..e72d5e4 100644
--- a/lib/filter/src/fir_semi_parallel.vhd
+++ b/lib/filter/src/fir_semi_parallel.vhd
@@ -145,7 +145,7 @@ coef_we_gen:
 			i 			:= to_integer(saddr);
 			coef_we		<= (others => '0');
 			coef_we(i)	<= '1';
-			coef_din	<= unsigned(h_in);
+			coef_din	<= unsigned(to_signed(h_in));
 			coef_addr	<= caddr;
 		end if;	
 	end process;