diff --git a/programs/use_fasm.lua b/programs/use_fasm.lua
index a008bd7546..dc738dc27d 100644
--- a/programs/use_fasm.lua
+++ b/programs/use_fasm.lua
@@ -7,7 +7,7 @@ function add_include(dir)
     else INCLUDES = INCLUDES .. ";" .. dir
   end
   if tup.getconfig("TUP_PLATFORM") == "win32"
-    then env_prefix = "set INCLUDE='$(INCLUDES)'&&"
+    then env_prefix = "set INCLUDE=$(INCLUDES)&&"
     else env_prefix = "INCLUDE='$(INCLUDES)' "
   end
   FASM = env_prefix .. FASM_DEFAULT