diff --git a/runbuild b/runbuild
index 196c8f5..a59120a 100755
--- a/runbuild
+++ b/runbuild
@@ -52,6 +52,25 @@ fi
 
 make -j"$CORES" package/openwisp-config/compile || make -j1 V=s package/openwisp-config/compile || exit 1
 
+# Ensure usign tool is available (required for package index generation)
+# Even when generating unsigned indexes, OpenWRT's Makefile needs usign for SHA-512 padding workaround
+if [ ! -f staging_dir/host/bin/usign ]; then
+	echo "usign not found, building tools..."
+	make -j"$CORES" tools/install || make -j1 V=s tools/install
+fi
+
+# Generate package index with checksums (unsigned - no usign needed)
+make package/index SIGNED_PACKAGES= V=s
+
+# Filter Packages file to include only openwisp packages and save as checksum file
+mkdir -p "$BUILD_DIR/openwrt/bin/packages/$COMPILE_TARGET/openwisp"
+awk '
+	/^Package: openwisp-/ {flag=1}
+	flag {print}
+	/^$/ {flag=0}
+' "$BUILD_DIR/openwrt/bin/packages/$COMPILE_TARGET/Packages" \
+	>"$BUILD_DIR/openwrt/bin/packages/$COMPILE_TARGET/openwisp/Packages.sha256.checksum"
+
 mv "$BUILD_DIR"/openwrt/bin/packages/"$COMPILE_TARGET"/openwisp "$VERSIONED_DIR"
 
 rm "$LATEST_LINK" || true