diff --git a/mcs/class/aot-compiler/Makefile b/mcs/class/aot-compiler/Makefile
index d070a293e36..39b823e4019 100644
--- a/mcs/class/aot-compiler/Makefile
+++ b/mcs/class/aot-compiler/Makefile
@@ -45,8 +45,8 @@ ifndef SKIP_AOT
 profile_file:=$(wildcard $(topdir)/class/lib/build/csc.*.aotprofile)
 ifneq ($(profile_file),)
 comma:=,
-space:=
-space+=
+empty:=
+space:= $(empty) $(empty)
 profile_arg:=$(subst $(space)$(comma),$(comma),$(foreach pf,$(profile_file),$(comma)profile=$(strip $(pf))))
 endif