diff --git a/lib/FIFO/sim/tb_fifo_async.fdo b/lib/FIFO/sim/tb_fifo_async.fdo
index ad9ac50..aacbd3e 100644
--- a/lib/FIFO/sim/tb_fifo_async.fdo
+++ b/lib/FIFO/sim/tb_fifo_async.fdo
@@ -1,5 +1,7 @@
 ## NOTE:  Do not edit this file.
 ##
+if {[file exists work]} {vdel -lib work -all}
+
 vlib work
 vcom -explicit  -93 "../src/fifo_ctrl_pkg.vhd"
 vcom -explicit  -93 "../src/gray_counter.vhd"
diff --git a/lib/FIFO/sim/tb_fifo_sync.fdo b/lib/FIFO/sim/tb_fifo_sync.fdo
index b247a72..f85715c 100644
--- a/lib/FIFO/sim/tb_fifo_sync.fdo
+++ b/lib/FIFO/sim/tb_fifo_sync.fdo
@@ -1,5 +1,7 @@
 ## NOTE:  Do not edit this file.
 ##
+if {[file exists work]} {vdel -lib work -all}
+
 vlib work
 vcom -explicit  -93 "../src/fifo_ctrl_pkg.vhd"
 vcom -explicit  -93 "../../rams/dpram_1w1r2c_ra_sim.vhd"
diff --git a/lib/FIFO/sim/tb_gray_counter.fdo b/lib/FIFO/sim/tb_gray_counter.fdo
index b619f71..d629753 100644
--- a/lib/FIFO/sim/tb_gray_counter.fdo
+++ b/lib/FIFO/sim/tb_gray_counter.fdo
@@ -1,5 +1,7 @@
 ## NOTE:  Do not edit this file.
 ##
+if {[file exists work]} {vdel -lib work -all}
+
 vlib work
 vcom -explicit  -93 "../src/fifo_ctrl_pkg.vhd"
 vcom -explicit  -93 "../src/gray_counter.vhd"