diff --git a/cover/gather_coverage.sh b/cover/gather_coverage.sh
new file mode 100755
index 000000000..9026745a1
--- /dev/null
+++ b/cover/gather_coverage.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+# This scripts copies all the coverage reports from various circle shards,
+# merges them and produces a complete report.
+
+set -ex
+DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+DESTINATION=$1
+FROMDIR=$2
+mkdir -p $DESTINATION
+
+if [ -n "$CIRCLECI" ]; then
+    for i in $(seq 1 $(($CIRCLE_NODE_TOTAL - 1))); do
+        scp node$i:$FROMDIR/* $DESTINATION || true
+    done
+fi
+
+go get github.com/weaveworks/build-tools/cover
+cover $DESTINATION/* >profile.cov
+go tool cover -html=profile.cov -o coverage.html
+go tool cover -func=profile.cov -o coverage.txt
+tar czf coverage.tar.gz $DESTINATION
diff --git a/rebuild-image b/rebuild-image
index 0eb3cff3c..df3a371c4 100755
--- a/rebuild-image
+++ b/rebuild-image
@@ -17,12 +17,12 @@ rebuild() {
     mkdir -p $CACHEDIR
     rm $CACHEDIR/$SAVEDNAME* || true
     docker build -t $IMAGENAME $IMAGEDIR
-	docker save $IMAGENAME:latest > $CACHEDIR/$SAVEDNAME-$CIRCLE_SHA1
+	docker save $IMAGENAME:latest | gzip - > $CACHEDIR/$SAVEDNAME-$CIRCLE_SHA1.gz
 }
 
 # Get the revision the cached image was build at
 cached_image_rev() {
-	find $CACHEDIR -name "$SAVEDNAME-*" -type f | sed 's/[^\-]*\-//'
+	find $CACHEDIR -name "$SAVEDNAME-*" -type f | sed -n 's/^[^\-]*\-\([a-z0-9]*\).gz$/\1/p'
 }
 
 # Have there been any revision beween $1 and $2
@@ -60,4 +60,4 @@ fi
 
 # we didn't rebuild; import cached version
 echo ">>> No changes found, importing cached image"
-docker load -i $CACHEDIR/$SAVEDNAME-$cached_revision
+zcat $CACHEDIR/$SAVEDNAME-$cached_revision.gz | docker load