diff --git a/docker/gitian-bitcoin-host/Dockerfile b/docker/gitian-bitcoin-host/Dockerfile
index 397e3ae..b652f35 100644
--- a/docker/gitian-bitcoin-host/Dockerfile
+++ b/docker/gitian-bitcoin-host/Dockerfile
@@ -13,11 +13,16 @@ COPY input-sources/ /home/debian/input-sources/
 COPY bin/build-bitcoin.sh /home/debian/
 COPY bin/sign.sh /home/debian/
 
-COPY gitian-gbuild.patch /home/debian/
-
 ## patch to not attempt removal of build directory (will be a volume)
+COPY gitian-gbuild.patch /home/debian/
 RUN cd gitian-builder && patch -p1 < ../gitian-gbuild.patch && rm ../gitian-gbuild.patch
 
+## patch to write asserts only (best for detached signatures)
+COPY gitian-gasserts.patch /home/debian/
+RUN cd gitian-builder && cp bin/gsign bin/gasserts && patch -p1 < ../gitian-gasserts.patch && rm ../gitian-gasserts.patch
+
 WORKDIR /home/debian
 
-RUN chown -R debian.debian input-sources build-bitcoin.sh sign.sh
+RUN mkdir gitian-builder/inputs
+
+RUN chown -R debian.debian input-sources build-bitcoin.sh sign.sh gitian-builder/inputs
diff --git a/docker/gitian-bitcoin-host/gitian-gasserts.patch b/docker/gitian-bitcoin-host/gitian-gasserts.patch
new file mode 100644
index 0000000..61fe8c8
--- /dev/null
+++ b/docker/gitian-bitcoin-host/gitian-gasserts.patch
@@ -0,0 +1,8 @@
+--- a/bin/gasserts	2015-01-13 15:39:29.000000000 +0000
++++ b/bin/gasserts	2015-01-14 13:52:49.287255738 +0000
+@@ -85,4 +85,3 @@
+ File.open(assert_path, "w") do |io|
+   io.write result.to_yaml
+ end
+-system!("gpg --detach-sign -u \"#{signer}\" \"#{assert_path}\"")
+
diff --git a/docker/scripts/bitcoin-gitian-build.sh b/docker/scripts/bitcoin-gitian-build.sh
index b3e2e54..590dd68 100755
--- a/docker/scripts/bitcoin-gitian-build.sh
+++ b/docker/scripts/bitcoin-gitian-build.sh
@@ -12,6 +12,12 @@
 
 SCRIPTS=$(dirname $(readlink -m $0)) || exit $?
 
+## place this file in script's directory in order to build for Mac OS X
+SDK=MacOSX10.7.sdk.tar.gz
+
+## change the assert directory as desired
+SIGNER="$USER"
+
 if [ $# -lt 1 ]; then
 	echo "Usage: gitian-build.sh linux [win] [osx] [...]" 1>&2
 	exit 1
@@ -41,8 +47,12 @@ set -o pipefail && \
 MOSTRECENT="$(curl -s https://api.github.com/repos/bitcoin/bitcoin/tags | jq -r '.[0].name' | awk '{ print substr($0, 2) }')" || exit $?
 
 ## volumes inside container that are provided externally (bind mount)
+LRESULT="$SCRIPTS/gitian-result"
+LSIGS="$SCRIPTS/gitian-sigs"
 LSOURCE="$SCRIPTS/gitian-cache"
 LDEST="$SCRIPTS/gitian-built"
+CRESULT="/home/debian/gitian-builder/result"
+CSIGS="/home/debian/gitian.sigs"
 CSOURCE="/home/debian/gitian-builder/cache"
 CDEST="/home/debian/gitian-builder/build"
 
@@ -53,17 +63,25 @@ function run_all() {
 
 	for OS in "$@"; do
 		mkdir -p "$LSOURCE/${OS}" && \
-		rm -rf "$LDEST" && \
-		mkdir -p "$LDEST" || return $?
+		rm -rf "$LDEST/${OS}" && \
+		mkdir -p "$LDEST/${OS}" || return $?
 	done
-	mkdir -p "$LSOURCE" "$LDEST" && \
-	chown -R 1000.1000 "$LDEST" "$LSOURCE" || return $?
+	mkdir -p "$LSIGS/$USER" && \
+	mkdir -p "$LSOURCE" && \
+	mkdir -p "$LRESULT" && \
+	chown -R 1000.1000 "$LDEST" "$LSOURCE" "$LSIGS" "$LRESULT" || return $?
 
 	for OS in "$@"; do
-		echo "docker run -d --privileged -v $LSOURCE/${OS}:${CSOURCE} -v $LDEST/${OS}:$CDEST gdm85/gitian-bitcoin-host" || return $?
+		echo "docker run -d --privileged -v $LRESULT:$CRESULT -v $LSIGS:$CSIGS -v $LSOURCE/${OS}:${CSOURCE} -v $LDEST/${OS}:$CDEST gdm85/gitian-bitcoin-host" || return $?
 	done | $PARALLEL
 }
 
+function inject_mac_sdk() {
+	local CID="$1"
+
+	docker-inject "$CID" "$SCRIPTS/$SDK" /home/debian/gitian-builder/inputs/
+}
+
 function build_all() {
 	local ALL=($@)
 	local LEN=$(($#/2))
@@ -71,15 +89,25 @@ function build_all() {
 	local OSES=("${ALL[@]:$LEN}")
 	local CID
 	local OS
-	local IP
 
 	local I=0
 	for CID in $CREATED; do
 		OS=${OSES[$I]}
 
+		if [[ "$OS" == "osx" ]]; then
+			inject_mac_sdk "$CID" || return $?
+		fi
+		let I+=1
+	done
+
+	I=0
+	for CID in $CREATED; do
+		OS=${OSES[$I]}
+
 		## first, fix rights of mounted volumes
-		echo -n "docker exec $CID chown -R debian.debian '$CSOURCE' '$CDEST' && " && \
-		echo "docker exec $CID su -c 'cd /home/debian && source .bash_profile && ./build-bitcoin.sh $MOSTRECENT ${OS}' debian"
+#		echo -n "docker exec $CID chown -R debian.debian '$CSOURCE' '$CDEST' && " && \
+		echo -n "docker exec $CID su -c 'cd /home/debian && source .bash_profile && ./build-bitcoin.sh $MOSTRECENT ${OS} && " && \
+		echo    "cd gitian-builder && ./bin/gasserts --signer $SIGNER --release ${MOSTRECENT} --destination ../gitian.sigs/ ../bitcoin/contrib/gitian-descriptors/gitian-${OS}.yml' debian"
 		let I+=1
 	done | $PARALLEL
 }