diff --git a/Common/sim/compile_simprim.do b/Common/sim/compile_simprim.do
index 0d97d06..9f7ba37 100644
--- a/Common/sim/compile_simprim.do
+++ b/Common/sim/compile_simprim.do
@@ -1,6 +1,6 @@
 vlib simprim
 
-set XILINX C:/Programme/Xilinx101/ISE
+set XILINX $env(XILINX)
 
 vcom -93 -work simprim  $XILINX/vhdl/src/simprims/simprim_Vcomponents_mti.vhd
 vcom -93 -work simprim  $XILINX/vhdl/src/simprims/simprim_Vpackage_mti.vhd
diff --git a/Common/sim/compile_unisim.do b/Common/sim/compile_unisim.do
index 6e91db1..4aec199 100644
--- a/Common/sim/compile_unisim.do
+++ b/Common/sim/compile_unisim.do
@@ -1,6 +1,6 @@
 vlib unisim
 
-set XILINX C:/Programme/Xilinx101/ISE
+set XILINX $env(XILINX)
 
 vcom -93 -work unisim  $XILINX/vhdl/src/unisims/unisim_vpkg.vhd
 vcom -93 -work unisim  $XILINX/vhdl/src/unisims/unisim_vcomp.vhd