diff --git a/include/env/get.sh b/include/env/get.sh
index 9cd88174..67fdf976 100644
--- a/include/env/get.sh
+++ b/include/env/get.sh
@@ -242,7 +242,7 @@ bad_checksum()
 	e "$2" f missing && \
 		return 0
 
-	build_sbase
+	eval "$build_sbase"
 	csum="$(x_ "$sha512sum" "$2" | awk '{print $1}')" || \
 	    err "!sha512 '$2' $1" bad_checksum "$@"
 
diff --git a/include/fw/vendor.sh b/include/fw/vendor.sh
index 05f8b226..45cfa19a 100644
--- a/include/fw/vendor.sh
+++ b/include/fw/vendor.sh
@@ -473,7 +473,7 @@ prep()
 
 mksha512()
 {
-	build_sbase
+	eval "$build_sbase"
 
 	[ "${1%/*}" != "$1" ] && \
 		x_ cd "${1%/*}"
@@ -571,7 +571,7 @@ vfile()
 # must be called from a subshell
 check_vendor_hashes()
 {
-	build_sbase
+	eval "$build_sbase"
 
 	x_ cd "$tmpromdir"
 
diff --git a/include/lib.sh b/include/lib.sh
index 03758982..74b75283 100644
--- a/include/lib.sh
+++ b/include/lib.sh
@@ -8,6 +8,8 @@
 cbfstool="elf/coreboot/default/cbfstool"
 rmodtool="elf/coreboot/default/rmodtool"
 
+build_sbase="[ ! -f \"\$sha512sum\" ] && x_ make -C util/sbase" # macro!
+
 newvar()
 {
 	printf "%s\n" "$*" | \
@@ -112,11 +114,6 @@ unpad_one_byte()
 	x_ mv "$unpaddedfile" "$1"
 }
 
-build_sbase()
-{
-	[ ! -f "$sha512sum" ] && x_ make -C "$xbmkpwd/util/sbase"; :
-}
-
 remkdir()
 {
 	x_ rm -Rf "$@"
diff --git a/mk b/mk
index 0611231e..f22aaf40 100755
--- a/mk
+++ b/mk
@@ -392,7 +392,7 @@ project_up_to_date()
 		    "$@"
 	fi
 
-	build_sbase
+	eval "$build_sbase"
 	fx_ "x_ util/sbase/sha512sum" find "$@" -type f -not -path \
 	    "*/.git*/*" | awk '{print $1}' > "$xbtmp/tmp.hash" || \
 	    err "!h $project $hashdir" \