diff --git a/README.rst b/README.rst
index 2c95f7c4b..1b8eb0716 100644
--- a/README.rst
+++ b/README.rst
@@ -104,6 +104,16 @@ conditions for (2), e.g. https://github.com/hsivonen/simd/issues/25
 obvious so documentation is less necessary, and dependent crates all do it
 correctly already.)
 
+Changed orig tarballs
+---------------------
+
+Sometimes the orig.tar generated by debcargo might change e.g. if you are using
+a newer version of debcargo and one of the dependencies relating to generating
+the tarball was updated and its behaviour changed - compression settings,
+tarball archive ordering, etc. This will cause your upload to get REJECTED by
+the Debian FTP archive for having a different orig.tar. In this case, set
+REUSE_EXISTING_ORIG_TARBALL=1 when running ``./release.sh``.
+
 ITPs
 ----
 
diff --git a/build.sh b/build.sh
index c4ba56f23..244733958 100755
--- a/build.sh
+++ b/build.sh
@@ -49,7 +49,14 @@ if shouldbuild ${DEBSRC}_${DEBVER}.dsc "$PKGNAME/debian/changelog" ]; then
 		mv "${DEBSRC}_${UPSVER}.orig.tar.gz" "${DEBSRC}_${UPSVER}.orig.tar.gz.new"
 		apt-get -t unstable source "${DEBSRC}" # "=${DEBVER}"
 		# check that old tarball contains same contents as new tarball
-		diff -q <(zcat "${DEBSRC}_${UPSVER}.orig.tar.gz.new") <(zcat "${DEBSRC}_${UPSVER}.orig.tar.gz")
+		if ! diff -ru \
+			  --label "${DEBSRC}_${UPSVER}.orig.tar.gz.new" \
+			  <(zcat  "${DEBSRC}_${UPSVER}.orig.tar.gz.new" | tar -tvvf-) \
+			  --label "${DEBSRC}_${UPSVER}.orig.tar.gz" \
+			  <(zcat  "${DEBSRC}_${UPSVER}.orig.tar.gz" | tar -tvvf-); then
+			read -p "contents differ, continue with old tarball or abort? [y/N] " x
+			if [ "$x" != "y" ]; then exit 1; fi
+		fi
 		( cd "$PKGNAME" && dpkg-buildpackage -d -S --no-sign )
 	fi
 	# sign if not UNRELEASED