diff --git a/Makefile b/Makefile
index f7909b601d..5343672372 100644
--- a/Makefile
+++ b/Makefile
@@ -87,7 +87,9 @@ ASTLDFLAGS+=$(LDOPTS)
 # Create OPTIONS variable
 OPTIONS=
 
-ASTTOPDIR:=$(shell pwd | sed -e 's/ /\\ /g')
+empty:=
+space:=$(empty) $(empty)
+ASTTOPDIR:=$(subst $(space),\$(space),$(CURDIR))
 
 # Overwite config files on "make samples"
 OVERWRITE=y