script_ext = ".sh"
         shell = ["bash"]
         build_script_contents = "# Autogenerated by LiteX / git: " + tools.get_litex_git_revision() + "\nset -e\n"
+        litex_env_ise = os.getenv("LITEX_ENV_ISE", None)
+        if litex_env_ise is not None:
+            build_script_contents += "source " + os.path.join(litex_env_ise, "settings64.sh\n")
         fail_stmt = ""
     if mode == "edif":
         ext = "ngo"
 
         tools.write_to_file(script_file, script_contents)
     else:
         script_contents = "# Autogenerated by LiteX / git: " + tools.get_litex_git_revision() + "\nset -e\n"
+        litex_env_vivado = os.getenv("LITEX_ENV_VIVADO", None)
+        if litex_env_vivado is not None:
+            script_contents += "source " + os.path.join(litex_env_vivado, "settings64.sh\n")
         script_contents += "vivado -mode batch -source " + build_name + ".tcl\n"
         script_file = "build_" + build_name + ".sh"
         tools.write_to_file(script_file, script_contents)