diff --git a/lib/libnetwork.lib.in b/lib/libnetwork.lib.in
index afcc9b5..673332a 100644
--- a/lib/libnetwork.lib.in
+++ b/lib/libnetwork.lib.in
@@ -980,6 +980,9 @@ function git.create_tarball() {
          if [ "${git_branch/@*}" != "${git_branch}" ]; then
             git_commit="${git_branch/*@}"
             git_branch="${git_branch/@*}"
+            if [ ! "${git_commit}" ]; then
+               notify.error "$FUNCNAME: cannot checkout empty commit"
+            fi
          fi
          notify.debug "$FUNCNAME: git_branch = \"$git_branch\""
          if [ "${git_commit}" ]; then
@@ -1053,7 +1056,11 @@ not the expected package version"" (${NOTE}${today}git${NORM})..."
 
    if [ "${git_commit}" ]; then
       cd ${pck_tarball}
-      git checkout ${git_commit}
+      git checkout ${git_commit} || {
+         popd &>/dev/null
+         rm -fr $tmpgitdir
+         notify.error $"cannot checkout the specified tag";
+      }
       cd ..
    fi