diff --git a/util/crossgcc/buildgcc b/util/crossgcc/buildgcc
index a29a338..02a7d82 100755
--- a/util/crossgcc/buildgcc
+++ b/util/crossgcc/buildgcc
@@ -125,6 +125,26 @@
 			fi
 		fi
 	fi
+	if [ "`echo $1 | cut -b -3`" = "sha" ]; then
+		if [ $UNAME = "FreeBSD" ]; then
+			if test -x "`which sha1 2>/dev/null`"; then
+				echo sha1
+				return
+			fi
+		fi
+		if [ $UNAME = "NetBSD" ]; then
+			if test -x "`which cksum 2>/dev/null`"; then
+				echo cksum -a `echo $1 | sed -e 's,sum,,'`
+				return
+			fi
+		fi
+		if [ $UNAME = "Darwin" ]; then
+			if test -x "`which openssl 2>/dev/null`"; then
+				echo openssl `echo $1 | sed -e 's,sum,,'`
+				return
+			fi
+		fi
+	fi
 	printf "${RED}ERROR:${red} Missing tool: Please install $1 (eg using your OS packaging system)${NC}\n" >&2
 	[ -z "$3" ] && exit 1
 	false
@@ -151,6 +171,10 @@
 	true
 }
 
+SHA1SUM=`searchtool sha1sum`
+SHA512SUM=`searchtool sha512sum`
+CHECKSUM=$SHA1SUM
+
 cleanup()
 {
 	printf "Cleaning up temporary files... "
@@ -295,10 +319,25 @@
 	    $IASL_ARCHIVE $PYTHON_ARCHIVE $EXPAT_ARCHIVE; do
 	FILE=`basename $ARCHIVE`
 	printf " * $FILE "
-	test -f tarballs/$FILE && printf "(cached)" || (
+
+	##create the sum
+	#test -f sum/$FILE.cksum || (
+	#	$CHECKSUM tarballs/$FILE > sum/$FILE.cksum
+	#	continue
+	#)
+
+	test -f tarballs/$FILE && \
+			(test -z "$CHECKSUM" || \
+			test "`cat sum/$FILE.cksum 2>/dev/null | sed -e 's,.*\([0-9a-f]\{40\}\).*,\1,'`" = "`$CHECKSUM tarballs/$FILE 2>/dev/null | sed -e 's,.*\([0-9a-f]\{40\}\).*,\1,'`" ) && \
+			printf "(cached)" || (
 		printf "(downloading)"
+		rm -f tarballs/$FILE
 		cd tarballs
 		wget --no-check-certificate -q $ARCHIVE
+		cd ..
+		test ! -f sum/$FILE.cksum && test -f tarballs/$FILE && \
+			(test -z "$CHECKSUM" || $CHECKSUM tarballs/$FILE > sum/$FILE.cksum ) && \
+			printf "(checksum created. ${RED}Note. Please upload sum/$FILE.cksum if the corresponding archive is upgraded.${NC})"
 	)
 	test -f tarballs/$FILE || \
 		printf "\n${RED}Failed to download $FILE.${NC}\n"