diff --git a/config/functions b/config/functions
index 6e803d003e..b4c21da7b2 100644
--- a/config/functions
+++ b/config/functions
@@ -760,11 +760,16 @@ get_pkg_directory() {
 }
 
 calculate_stamp() {
-  local stamp
+  local stamp data
+
   stamp="$PKG_DIR $PROJECT_DIR/$PROJECT/patches/$PKG_NAME"
   [ -n "$DEVICE" ] && stamp+=" $PROJECT_DIR/$PROJECT/devices/$DEVICE/patches/$PKG_NAME"
   [ -n "$PKG_NEED_UNPACK" ] && stamp+=" $PKG_NEED_UNPACK"
-  find ${stamp} -exec sha256sum {} \; 2>/dev/null | sed "s/ ${ROOT//\//\\/}\// /" | sort | sha256sum | cut -d" " -f1
+
+  data="$(find ${stamp} -exec sha256sum {} \; 2>/dev/null | sed "s/ ${ROOT//\//\\/}\// /")"
+  [ -n "${PKG_STAMP}" ] && data+=$'\n'"$(echo "${PKG_STAMP}" | sha256sum)"
+
+  echo "${data}" | sort | sha256sum | cut -d" " -f1
 }
 
 target_has_feature() {
diff --git a/packages/linux/package.mk b/packages/linux/package.mk
index c40a50f0c6..e542b78ad4 100644
--- a/packages/linux/package.mk
+++ b/packages/linux/package.mk
@@ -11,6 +11,7 @@ PKG_DEPENDS_INIT="toolchain"
 PKG_NEED_UNPACK="$LINUX_DEPENDS"
 PKG_LONGDESC="This package contains a precompiled kernel image and the modules."
 PKG_IS_KERNEL_PKG="yes"
+PKG_STAMP="$KERNEL_TARGET $KERNEL_MAKE_EXTRACMD $KERNEL_UBOOT_EXTRA_TARGET"
 
 PKG_PATCH_DIRS="$LINUX"
 
diff --git a/packages/tools/u-boot/package.mk b/packages/tools/u-boot/package.mk
index d11703c27a..f0d929d7a0 100644
--- a/packages/tools/u-boot/package.mk
+++ b/packages/tools/u-boot/package.mk
@@ -9,6 +9,7 @@ PKG_DEPENDS_TARGET="toolchain dtc:host"
 PKG_LICENSE="GPL"
 PKG_LONGDESC="Das U-Boot is a cross-platform bootloader for embedded systems."
 PKG_IS_KERNEL_PKG="yes"
+PKG_STAMP="$UBOOT_SYSTEM"
 
 PKG_NEED_UNPACK="$PROJECT_DIR/$PROJECT/bootloader"
 [ -n "$DEVICE" ] && PKG_NEED_UNPACK+=" $PROJECT_DIR/$PROJECT/devices/$DEVICE/bootloader"
diff --git a/scripts/build b/scripts/build
index db6ac4f707..13a3545078 100755
--- a/scripts/build
+++ b/scripts/build
@@ -49,8 +49,6 @@ if [ -f $STAMP ]; then
     rm -f $STAMP
   elif [ ! "$BUILD_WITH_DEBUG" = "$STAMP_BUILD_WITH_DEBUG" ]; then
     rm -f $STAMP
-  elif [ "${PKG_NAME}" = "u-boot" -a ! "$UBOOT_SYSTEM" = "$STAMP_UBOOT_SYSTEM" ]; then
-    rm -f $STAMP
   else
     # stamp matched: already built, do nothing
     pkg_lock_status "UNLOCK" "${PKG_NAME}:${TARGET}" "build" "already built"
@@ -502,8 +500,5 @@ PKG_DEEPHASH=$(calculate_stamp)
 for i in PKG_NAME PKG_DEEPHASH BUILD_WITH_DEBUG; do
   echo "STAMP_$i=\"${!i}\"" >> $STAMP
 done
-if [ "${PKG_NAME}" = "u-boot" ]; then
-  echo "STAMP_UBOOT_SYSTEM=\"${UBOOT_SYSTEM}\"" >> $STAMP
-fi
 
 pkg_lock_status "UNLOCK" "${PKG_NAME}:${TARGET}" "build" "built"