diff --git a/lib/emac/sim/tb_crc32.fdo b/lib/emac/sim/tb_crc32.fdo
index 241deb5..15063e7 100644
--- a/lib/emac/sim/tb_crc32.fdo
+++ b/lib/emac/sim/tb_crc32.fdo
@@ -1,6 +1,8 @@
 ## NOTE:  Do not edit this file.
 ## Autogenerated by ProjNav (creatfdo.tcl) on Thu Jul 06 20:49:07 Westeuropäische Sommerzeit 2006
 ##
+if {[file exists work]} {vdel -lib work -all}
+
 vlib work
 vcom -explicit  -93 "../../misc/utils_pkg.vhd"
 vcom -explicit  -93 "../src/crc32.vhd"
diff --git a/lib/emac/sim/tb_serdes.fdo b/lib/emac/sim/tb_serdes.fdo
index dc5d8f1..14643c5 100644
--- a/lib/emac/sim/tb_serdes.fdo
+++ b/lib/emac/sim/tb_serdes.fdo
@@ -1,6 +1,8 @@
 ## NOTE:  Do not edit this file.
 ## Autogenerated by ProjNav (creatfdo.tcl) on Thu Jul 06 20:49:07 Westeuropäische Sommerzeit 2006
 ##
+if {[file exists work]} {vdel -lib work -all}
+
 vlib work
 vcom -explicit  -93 "../../misc/utils_pkg.vhd"
 vcom -explicit  -93 "../src/piso.vhd"