diff --git a/sbin/prepareWorkspace.sh b/sbin/prepareWorkspace.sh
index 6792fe865..886f2c00e 100644
--- a/sbin/prepareWorkspace.sh
+++ b/sbin/prepareWorkspace.sh
@@ -51,10 +51,11 @@ copyFromDir() {
 # this is workarounding --strip-components 1 missing on gnu tar
 # it requires  absolute tar-filepath as it changes dir and is hardcoded to one
 # similar approach can be used also for zip in future
-untarGnuAbsPathWithStripComponents1() {
+# warning! this method do not merge if (parts of!) destination exists.
+unpackGnuAbsPathWithStrip1Component() {
   local tmp=$(mktemp -d)
   pushd "$tmp" > /dev/null
-    tar "$@"
+    "$@"
   popd  > /dev/null
   mv "$tmp"/*/* .
   mv "$tmp"/*/.* . || echo "no hidden files in tarball"
@@ -62,18 +63,30 @@ untarGnuAbsPathWithStripComponents1() {
   rmdir "$tmp"
 }
 
+untarGnuAbsPathWithStrip1Component() {
+  unpackGnuAbsPathWithStrip1Component tar -xf "$@"
+}
+
+unzipGnuAbsPathWithStrip1Component() {
+  unpackGnuAbsPathWithStrip1Component unzip "$@"
+}
+
 unpackFromArchive() {
   echo "Extracting OpenJDK source tarball ${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]} to $(pwd)/${BUILD_CONFIG[OPENJDK_SOURCE_DIR]} to build the binary"
   # If the tarball contains .git files, they should be ignored later
-  # todo, support also zips?
   pushd "./${BUILD_CONFIG[OPENJDK_SOURCE_DIR]}"
-    local topLevelItems=$(tar --exclude='*/*' -tf  "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]}"  | grep "/$" -c) || local topLevelItems=1
-    if [ "$topLevelItems" -eq "1" ] ; then
-      echo "Source tarball contains exactly one directory"
-      untarGnuAbsPathWithStripComponents1 -xf "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]}"
+    if [ "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]: -4}" == ".zip" ] ; then
+        echo "Source zip unpacked as if it contains exactly one directory"
+        unzipGnuAbsPathWithStrip1Component "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]}"
     else
-      echo "Source tarball does not contain a top level directory"
-      tar -xf "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]}"
+      local topLevelItems=$(tar --exclude='*/*' -tf  "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]}" | grep "/$" -c) || local topLevelItems=1
+      if [ "$topLevelItems" -eq "1" ] ; then
+        echo "Source tarball contains exactly one directory"
+        untarGnuAbsPathWithStrip1Component "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]}"
+      else
+        echo "Source tarball does not contain a top level directory"
+        tar -xf "${BUILD_CONFIG[OPENJDK_LOCAL_SOURCE_ARCHIVE_ABSPATH]}"
+      fi
     fi
     rm -rf "build"
   popd