diff --git a/cores/VIC20/source/vic20_zxuno_v4.ucf b/cores/VIC20/source/vic20_zxuno_v4.ucf
index bab70a4..1218e0a 100644
--- a/cores/VIC20/source/vic20_zxuno_v4.ucf
+++ b/cores/VIC20/source/vic20_zxuno_v4.ucf
@@ -23,8 +23,8 @@ NET O_AUDIO_R         LOC="P9"   | IOSTANDARD = LVCMOS33 | SLEW = SLOW | DRIVE =
 NET EAR               LOC="P94"  | IOSTANDARD = LVCMOS33;
 
 # Keyboard and mouse
-NET I_PS2_CLK         LOC="P99"  | IOSTANDARD = LVCMOS33 | DRIVE = 8 | SLEW = SLOW ; 
-NET I_PS2_DATA        LOC="P98"  | IOSTANDARD = LVCMOS33 | DRIVE = 8 | SLEW = SLOW ; 
+NET I_PS2_CLK         LOC="P99"  | IOSTANDARD = LVCMOS33 | PULLUP;
+NET I_PS2_DATA        LOC="P98"  | IOSTANDARD = LVCMOS33 | PULLUP; 
 #NET "mouseclk"        LOC="P95"  | IOSTANDARD = LVCMOS33 | PULLUP;
 #NET "mousedata"       LOC="P97"  | IOSTANDARD = LVCMOS33 | PULLUP;