diff --git a/scripts/admin/build-package-tarballs.sh b/scripts/admin/build-package-tarballs.sh
index 3a2b343a7f..0a912965f3 100755
--- a/scripts/admin/build-package-tarballs.sh
+++ b/scripts/admin/build-package-tarballs.sh
@@ -60,8 +60,10 @@ do
 
     # Create the tarball from the built package. In the tarball, the root
     # directory should be $ROOTDIR, so we replace the "." with that, using
-    # --transform (a  GNU tar extension).
-    "$GNUTAR" czf "$TARBALL" -C "$PACKAGE/.build" --transform 's/^\./'"$ROOTDIR"'/' .
+    # --transform (a GNU tar extension). Leave out the buildinfo.json file,
+    # which contains local paths and is only used to decide if we should rebuild
+    # a package from its corresponding source tree.
+    "$GNUTAR" czf "$TARBALL" -C "$PACKAGE/.build" --exclude buildinfo.json --transform 's/^\./'"$ROOTDIR"'/' .
 
     # this is used in build-release.sh, which constructs the release json.
     echo -n "    \"$PACKAGE\": \"$PACKAGE_VERSION\"" >> "$TOPDIR/.package_manifest_chunk"
diff --git a/tools/packages.js b/tools/packages.js
index a732487ea8..9ca418b082 100644
--- a/tools/packages.js
+++ b/tools/packages.js
@@ -1790,7 +1790,7 @@ _.extend(Package.prototype, {
     if (options.onlyIfUpToDate) {
       // Do we think we'll generate different contents than the tool that built
       // this package?
-      if (mainJson.buildVersion !== exports.BUILD_VERSION)
+      if (buildInfoJson.builtBy !== exports.BUILD_VERSION)
         return false;
 
       if (options.buildOfPath &&
@@ -1961,7 +1961,6 @@ _.extend(Package.prototype, {
 
       var mainJson = {
         format: "unipackage-pre1",
-        buildVersion: exports.BUILD_VERSION,
         summary: self.metadata.summary,
         internal: self.metadata.internal,
         slices: [],
@@ -1971,6 +1970,7 @@ _.extend(Package.prototype, {
       };
 
       var buildInfoJson = {
+        buildVersion: exports.BUILD_VERSION,
         dependencies: { files: {}, directories: {} },
         source: options.buildOfPath || undefined
       };